Methods employing and compositions containing defined oxidized phospholipids for prevention and treatment of atherosclerosis

ABSTRACT

Novel synthetic forms of etherified oxidized phospholipids and methods of utilizing same for preventing and treating atherosclerosis and other related disorders, as well as inflammatory disorders, immune mediated diseases, autoimmune diseases and proliferative disorders, are provided. In addition, methods of synthesizing etherified and esterified oxidized phospholipids and of using same for preventing and treating atherosclerosis and other related disorders are also provided.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/183,884, filed on Jul. 19, 2005, which is a divisional of U.S. patentapplication Ser. No. 10/718,596, filed on Nov. 24, 2003, now U.S. Pat.No. 7,186,704, issued on Mar. 6, 2007, which is a divisional of U.S.patent application Ser. No. 10/445,347, filed on May 27, 2003, now U.S.Pat. No. 6,838,452, issued on Jan. 4, 2005, which is aContinuation-In-Part (CIP) of PCT Patent Application No. PCT/IL01/01080,filed on Nov. 22, 2001, which claims the benefit of U.S. ProvisionalPatent Application No. 60/252,574, filed on Nov. 24, 2000.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to defined, oxidized LDL (oxLDL)components for prevention and treatment of atherosclerosis and relateddiseases and disorders, as well as other inflammatory, immune mediated,autoimmune and proliferative diseases and disorders and, moreparticularly, to methods and compositions employing oxidizedphospholipids effective in inducing mucosal tolerance and inhibitinginflammatory processes.

Cardiovascular disease is a major health risk throughout theindustrialized world. Atherosclerosis, the most prevalent ofcardiovascular diseases, is the principal cause of heart attack, stroke,and gangrene of the extremities, and as such, the principle cause ofdeath in the United States. Atherosclerosis is a complex diseaseinvolving many cell types and molecular factors (for a detailed review,see Ross, 1993, Nature 362: 801-809). The process, which occurs inresponse to insults to the endothelium and smooth muscle cells (SMCs) ofthe wall of the artery, consists of the formation of fibrofatty andfibrous lesions or plaques, preceded and accompanied by inflammation.The advanced lesions of atherosclerosis may occlude the arteryconcerned, and result from an excessive inflammatory-fibroproliferativeresponse to numerous different forms of insult. For example, shearstresses are thought to be responsible for the frequent occurrence ofatherosclerotic plaques in regions of the circulatory system whereturbulent blood flow occurs, such as branch points and irregularstructures.

The first observable event in the formation of an atherosclerotic plaqueoccurs when inflammatory cells such as monocyte-derived macrophagesadhere to the vascular endothelial layer and transmigrate through to thesub-endothelial space. Elevated plasma LDL levels lead to lipidengorgement of the vessel walls, with adjacent endothelial cellsproducing oxidized low density lipoprotein (LDL). In addition,lipoprotein entrapment by the extracellular matrix leads to progressiveoxidation of LDL by lipoxygenases, reactive oxygen species,peroxynitrite and/or myeloperoxidase. These oxidized LDL's are thentaken up in large amounts by vascular cells through scavenger receptorsexpressed on their surfaces.

Lipid-filled monocytes and smooth-muscle derived cells are called foamcells, and are the major constituent of the fatty streak. Interactionsbetween foam cells and the endothelial and smooth muscle cellssurrounding them produce a state of chronic local inflammation which caneventually lead to activation of endothelial cells, increased macrophageapoptosis, smooth muscle cell proliferation and migration, and theformation of a fibrous plaque (Hajjar, D P and Haberland, M E, J. BiolChem 1997 Sep. 12; 272(37):22975-78). Such plaques occlude the bloodvessels concerned and thus restrict the flow of blood, resulting inischemia, a condition characterized by a lack of oxygen supply intissues of organs due to inadequate perfusion. When the involvedarteries block the blood flow to the heart, a person is afflicted with a‘heart attack’; when the brain arteries occlude, the person experiencesa stroke. When arteries to the limbs narrow, the result is severe pain,decreased physical mobility and possibly the need for amputation.

Oxidized LDL has been implicated in the pathogenesis of atherosclerosisand atherothrombosis, by its action on monocytes and smooth musclecells, and by inducing endothelial cell apoptosis, impairinganticoagulant balance in the endothelium. Oxidized LDL also inhibitsanti-atherogenic HDL-associated breakdown of oxidized phospholipids(Mertens, A and Holvoet, P, FASEB J 2001 October; 15(12):2073-84). Thisassociation is also supported by many studies demonstrating the presenceof oxidized LDL in the plaques in various animal models ofatherogenesis; the retardation of atherogenesis through inhibition ofoxidation by pharmacological and/or genetic manipulations; and thepromising results of intervention trials with anti-oxidant vitamins(see, for example, Witztum J and Steinberg, D, Trends Cardiovasc Med2001 April-May; 11(34):93-102 for a review of current literature).Indeed, oxidized LDL and malondialdehyde (MDA)-modified LDL have beenrecently proposed as accurate blood markers for 1^(st) and 2^(nd) stagesof coronary artery disease (U.S. Pat. Nos. 6,309,888 to Holvoet et. al.and 6,255,070 to Witztum, et al.).

Reduction of LDL oxidation and activity has been the target of a numberof suggested clinical applications for treatment and prevention ofcardiovascular disease. Bucala, et al. (U.S. Pat. No. 5,869,534)discloses methods for the modulation of lipid peroxidation by reducingadvanced glycosylation end product, lipid characteristic of age-,disease- and diabetes-related foam cell formation. Tang et al., atIncyte Pharmaceuticals, Inc. (U.S. Pat. No. 5,945,308) have disclosedthe identification and proposed clinical application of a Human OxidizedLDL Receptor in the treatment of cardiovascular and autoimmune diseasesand cancer.

Atherosclerosis and Autoimmune Disease

Because of the presumed role of the excessiveinflammatory-fibroproliferative response in atherosclerosis andischemia, a growing number of researchers have attempted to define anautoimmune component of vascular injury. In autoimmune diseases theimmune system recognizes and attacks normally non-antigenic bodycomponents (autoantigens), in addition to attacking invading foreignantigens. The autoimmune diseases are classified as auto- (or self-)antibody mediated or cell mediated diseases. Typical autoantibodymediated autoimmune diseases are myasthenia gravis and idiopathicthrombocytopenic purpura (ITP), while typical cell mediated diseases areHashimoto's thyroiditis and type I (Juvenile) Diabetes.

The recognition that immune mediated processes prevail withinatherosclerotic lesions stemmed from the consistent observation oflymphocytes and macrophages in the earliest stages, namely the fattystreaks. These lymphocytes which include a predominant population ofCD4+ cells (the remainder being CD8+ cells) were found to be moreabundant over macrophages in early lesions, as compared with the moreadvanced lesions, in which this ratio tends to reverse. These findingsposed questions as to whether they reflect a primary immunesensitization to a possible antigen or alternatively stand as a mereepiphenomenon of a previously induced local tissue damage. Regardless ofthe factors responsible for the recruitment of these inflammatory cellsto the early plaque, they seem to exhibit an activated state manifestedby concomitant expression of MHC class II HLA-DR and interleukin (IL)receptor as well as leukocyte common antigen (CD45R0) and the very lateantigen 1 (VLA-1) integrin.

The on-going inflammatory reaction in the early stages of theatherosclerotic lesion may either be the primary initiating eventleading to the production of various cytokines by the local cells (i.eendothelial cells, macrophages, smooth muscle cells and inflammatorycells), or it may be that this reaction is a form of the body's defenseimmune system towards the hazardous process. Some of the cytokines whichhave been shown to be upregulated by the resident cells include TNF-α,IL-1, IL-2, IL-6, IL-8, IFN-γ and monocyte chemoattractant peptide-1(MCP-1). Platelet derived growth factor (PDGF) and insulin-like growthfactor (ILGF) which are expressed by all cellular constituents withinatherosclerotic plaques have also been shown to be overexpressed, thuspossibly intensifying the preexisting inflammatory reaction by aco-stimulatory support in the form of a mitogenic and chemotacticfactor. Recently, Uyemura et al. (Cross regulatory roles of IL-12 andIL-10 in atherosclerosis. J Clin Invest 1996 97; 2130-2138) haveelucidated type 1 T-cell cytokine pattern in human atheroscleroticlesions exemplified by a strong expression of IFN-γ but not IL-4 mRNA incomparison with normal arteries. Furthermore, IL-12—a T-cell growthfactor produced primarily by activated monocytes and a selective inducerof Th1 cytokine pattern, was found to be overexpressed within lesions asmanifested by the abundance of its major heterodimer form p70 and p40(its dominant inducible protein) mRNA.

Similar to the strong evidence for the dominance of the cellular immunesystem within the atherosclerotic plaque, there is also ample datasupporting the involvement of the local humoral immune system. Thus,deposition of immunoglobulins and complement components have been shownin the plaques in addition to the enhanced expression of the C3b andC3Bi receptors in resident macrophages.

Valuable clues with regard to the contribution of immune mediatedinflammation to the progression of atherosclerosis come from animalmodels. Immunocompromised mice (class I MHC deficient) tend to developaccelerated atherosclerosis as compared with immune competent mice.Additionally, treatment of C57BL/6 mice (Emeson E E, Shen M L.Accelerated atherosclerosis in hyperlipidemic C57BL/6 mice treated withcyclosporin A. Am J Pathol 1993; 142; 1906-1915) and New-Zealand Whiterabbits (Roselaar S E, Schonfeld G, Daugherty A. Enhanced development ofatherosclerosis in cholesterol fed rabbits by suppression of cellmediated immunity. J Clin Invest 1995; 96: 1389-1394) with cyclosporinA, a potent suppressor of IL-2 transcription resulted in a significantlyenhanced atherosclerosis under “normal” lipoprotein “burden”. Theselatter studies may provide insight into the possible roles of the immunesystem in counteracting the self-perpetuating inflammatory processwithin the atherosclerotic plaque.

Atherosclerosis is not a classical autoimmune disease, although some ofits manifestations such as the production of the plaque which obstructsthe blood vessels may be related to aberrant immune responsiveness. Inclassical autoimmune disease, one can often define very clearly thesensitizing autoantigen attacked by the immune system and thecomponent(s) of the immune system which recognize the autoantigen(humoral, i.e. autoantibody or cellular, i.e. lymphocytes). Above all,one can show that by passive transfer of these components of the immunesystem the disease can be induced in healthy animals, or in the case ofhumans the disease may be transferred from a sick pregnant mother to heroffspring. Many of the above are not prevailing in atherosclerosis. Inaddition, the disease definitely has common risk factors such ashypertension, diabetes, lack of physical activity, smoking and others,the disease affects elderly people and has a different geneticpreponderance than in classical autoimmune diseases.

Treatment of autoimmune inflammatory disease may be directed towardssupression or reversal of general and/or disease-specific immunereactivity. Thus Aiello, for example (U.S. Pat. Nos. 6,034,102 and6,114,395) discloses the use of estrogen-like compounds for treatmentand prevention of atherosclerosis and atherosclerotic lesion progressionby inhibition of inflammatory cell recruitment. Similarly, Medford etal. (U.S. Pat. No. 5,846,959) disclose methods for the prevention offormation of oxidized PUFA, for treatment of cardiovascular andnon-cardiovascular inflammatory diseases mediated by the cellularadhesion molecule VCAM-1. Furthermore, Falb (U.S. Pat. No. 6,156,500)designates a number of cell signaling and adhesion molecules abundant inatherosclerotic plaque and disease as potential targets ofanti-inflammatory therapies.

Since oxidized LDL has been clearly implicated in the pathogenesis ofatherosclerosis (see above), the contribution of these prominent plaquecomponents to autoimmunity in atheromatous disease processes has beeninvestigated.

Immune Responsiveness to Oxidized LDL

It is known that oxidized LDL (Ox LDL) is chemotactic for T-cells andmonocytes. Ox LDL and its byproducts are also known to induce theexpression of factors such as monocyte chemotactic factor 1, secretionof colony stimulating factor and platelet activating properties, all ofwhich are potent growth stimulants.

The active involvement of the cellular immune response inatherosclerosis has recently been substantiated by Stemme S., et al.(Proc Natl Acad Sci USA 1995; 92: 3893-97), who isolated CD4+ withinplaques clones responding to Ox LDL as stimuli. The clones correspondingto Ox LDL (4 out of 27) produced principally interferony rather thanIL-4. It remains to be seen whether the above T-cell clones representmere contact with the cellular immune system with the inciting strongimmunogen (Ox LDL) or that this reaction provides means of combating theapparently indolent atherosclerotic process.

The data regarding the involvement of the humoral mechanisms and theirmeaning are much more controversial. One recent study reported increasedlevels of antibodies against MDA-LDL, a metabolite of LDL oxidation, inwomen suffering from heart disease and/or diabetes (Dotevall, et al.,Clin Sci 2001 November; 101(5): 523-31). Other investigators havedemonstrated antibodies recognizing multiple epitopes on the oxidizedLDL, representing immune reactivity to the lipid and apolipoproteincomponents (Steinerova A., et al., Physiol Res 2001; 50(2): 131-41) inatherosclerosis and other diseases, such as diabetes, renovascularsyndrome, uremia, rheumatic fever and lupus erythematosus. Severalreports have associated increased levels of antibodies to Ox LDL withthe progression of atherosclerosis (expressed by the degree of carotidstenosis, severity of peripheral vascular disease etc.). Most recently,Sherer et al. (Cardiology 2001; 95(1):20-4) demonstrated elevated levelsof antibodies to cardiolipin, beta 2GPI and Ox LDL, in coronary heartdisease. Thus, there seems to be a consensus as to the presence of OxLDL antibodies in the form of immune complexes within atheroscleroticplaque, although the true significance of this finding has not beenestablished.

Antibodies to Ox LDL have been hypothesized as playing an active role inlipoprotein metabolism. Thus, it is known that immune complexes of OxLDL and its corresponding antibodies are taken up more efficiently bymacrophages in suspension as compared with Ox LDL. No conclusions can bedrawn from this consistent finding on the pathogenesis ofatherosclerosis since the question of whether the accelerated uptake ofOx LDL by the macrophages is beneficial or deleterious has not yet beenresolved.

Important data as to the significance of the humoral immune system inatherogenesis comes from animal models. It has been found thathyperimmunization of LDL-receptor deficient rabbits with homologousoxidized LDL, resulted in the production of high levels of anti-Ox LDLantibodies and was associated with a significant reduction in the extentof atherosclerotic lesions as compared with a control group exposed tophopsphate-buffered saline (PBS). A decrease in plaque formation hasalso been accomplished by immunization of rabbits with cholesterol richliposomes with the concomitant production of anti-cholesterolantibodies, yet this effect was accompanied by a 35% reduction in verylow density lipoprotein cholesterol levels.

Thus, both the pathogenic role of oxidized LDL components and theirimportance as autoantigens in atherosclerosis, as well as otherdiseases, have been extensively demonstrated in laboratory and clinicalstudies.

Mucosal Tolerance in Treatment of Autoimmune Disease

Recently, new methods and pharmaceutical formulations have been foundthat are useful for treating autoimmune diseases (and related T-cellmediated inflammatory disorders such as allograft rejection andretroviral-associated neurological disease). These treatments inducetolerance, orally or mucosally, e.g. by inhalation, using as tolerizersautoantigens, bystander antigens, or disease-suppressive fragments oranalogs of autoantigens or bystander antigens. Such treatments aredescribed, for example, in U.S. Pat. No. 5,935,577 to Weiner et al.Autoantigens and bystander antigens are defined below (for a generalreview of mucosal tolerance see Nagler-Anderson, C., Crit. Rev Immunol2000; 20(2):103-20). Intravenous administration of autoantigens (andfragments thereof containing immunodominant epitopic regions of theirmolecules) has been found to induce immune suppression through amechanism called clonal anergy. Clonal anergy causes deactivation ofonly immune attack T-cells specific to a particular antigen, the resultbeing a significant reduction in the immune response to this antigen.Thus, the autoimmune response-promoting T-cells specific to anautoantigen, once anergized, no longer proliferate in response to thatantigen. This reduction in proliferation also reduces the immunereactions responsible for autoimmune disease symptoms (such as neuraltissue damage that is observed in MS). There is also evidence that oraladministration of autoantigens (or immunodominant fragments) in a singledose and in substantially larger amounts than those that trigger “activesuppression” may also induce tolerance through anergy (or clonaldeletion).

A method of treatment has also been disclosed that proceeds by activesuppression. Active suppression functions via a different mechanism fromthat of clonal anergy. This method, discussed extensively in PCTApplication PCT/US93/01705, involves oral or mucosal administration ofantigens specific to the tissue under autoimmune attack. These arecalled “bystander antigens”. This treatment causes regulatory(suppressor) T-cells to be induced in the gut-associated lymphoid tissue(GALT), or bronchial associated lymphoid tissue (BALT), or mostgenerally, mucosa associated lymphoid tissue (MALT) (MALT includes GALTand BALT). These regulatory cells are released in the blood or lymphatictissue and then migrate to the organ or tissue afflicted by theautoimmune disease and suppress autoimmune attack of the afflicted organor tissue. The T-cells elicited by the bystander antigen (whichrecognize at least one antigenic determinant of the bystander antigenused to elicit them) are targeted to the locus of autoimmune attackwhere they mediate the local release of certain immunomodulatory factorsand cytokines, such as transforming growth factor beta (TGF-□),interleukin-4 (IL4), and/or interleukin-10 (IL-10). Of these, TGF-□ isan antigen-nonspecific immunosuppressive factor in that it suppressesimmune attack regardless of the antigen that triggers the attack.(However, because oral or mucosal tolerization with a bystander antigenonly causes the release of TGF-□ in the vicinity of autoimmune attack,no systemic immunosuppression ensues.) IL-4 and IL-10 are alsoantigen-nonspecific immunoregulatory cytokines. IL-4 in particularenhances (T helper Th₂) Th₂ response, i.e., acts on T-cell precursorsand causes them to differentiate preferentially into Th₂ cells at theexpense of Th₁ responses. IL-4 also indirectly inhibits Th₁exacerbation. IL-10 is a direct inhibitor of Th₁ responses. After orallytolerizing mammals afflicted with autoimmune disease conditions withbystander antigens, increased levels of TGF-□, IL-4 and IL-10 areobserved at the locus of autoimmune attack (Chen, Y. et al., Science,265:1237-1240, 1994). The bystander suppression mechanism has beenconfirmed by von Herreth et al., (J. Clin. Invest., 96:1324-1331,September 1996).

More recently, oral tolerance has been effectively applied in treatmentof animal models of inflammatory bowel disease by feeding probioticbacteria (Dunne, C, et al., Antonie Van Leeuwenhoek 1999 July-November;76(1-4):279-92), autoimmune glomerulonephritis by feeding glomerularbasement membrane (Reynolds, J. et al., J Am Soc Nephrol 2001 January;12(1); 61-70) experimental allergic encephalomyelitis (EAE, which is theequivalent of multiple sclerosis or MS), by feeding myelin basic protein(MBP), adjuvant arthritis and collagen arthritis, by feeding a subjectwith collagen and HSP-65, respectively. A Boston based company calledAutoimmune has carried out several human experiments for preventingdiabetes, multiple sclerosis, rheumatoid arthritis and uveitis. Theresults of the human experiments have been less impressive than thenon-human ones, however there has been some success with the preventionof arthritis.

Oral tolerance to autoantigens found in atherosclerotic plaque lesionshas also been investigated. Study of the epitopes recognized by T-cellsand Ig titers in clinical and experimental models of atherosclerosisindicated three candidate antigens for suppression of inflammation inatheromatous lesions: oxidized LDL, the stress-related heat shockprotein HSP 65 and the cardiolipin binding protein beta 2GP1. U.S.patent application Ser. No. 09/806,400 to Shoenfeld et al. (filed Sep.30, 1999), which is incorporated herein in its entirety, discloses thereduction by approximately 30% of atherogenesis in the arteries ofgenetically susceptible LDL-RD receptor deficient transgenic mice fedwith oxidized human LDL. This protective effect, however, was achievedby feeding a crude antigen preparation consisting of centrifuged,filtered and purified human serum LDL which had been subjected to alengthy oxidation process with Cu⁺⁺. Although significant inhibition ofatherogenesis was achieved, presumably via oral tolerance, noidentification of specific lipid antigens or immunogenic LDL componentswas made. Another obstacle encountered was the inherent instability ofthe crude oxidized LDL in vivo, due to enzymatic activity and uptake ofoxidized LDL by the liver and cellular immune mechanisms. It isplausible that a stable, more carefully defined oxidized LDL analogwould have provided oral tolerance of greater efficiency.

The induction of immune tolerance and subsequent prevention orinhibition of autoimmune inflammatory processes has been demonstratedusing exposure to suppressive antigens via mucosal sites other than thegut. The membranous tissue around the eyes, and the mucosa of the nasalcavity, as well as the gut, are exposed to many invading as well asself-antigens and possess mechanisms for immune reactivity. Thus, Rossi,et al. (Scand J Immunol 1999 August; 50(2):177-82) found that nasaladministration of gliadin was as effective as intravenous administrationin downregulating the immune response to the antigen in a mouse model ofceliac disease. Similarly, nasal exposure to acetylcholine receptorantigen was more effective than oral exposure in delaying and reducingmuscle weakness and specific lymphocyte proliferation in a mouse modelof myasthenia gravis (Shi, F D. et al., J Immunol 1999 May 15; 162 (10):5757-63). Therefore, immunogenic compounds intended for mucosal as wellas intravenous or intraperitoneal administration should optimally beadaptable to nasal and other membranous routes of administration.

Thus, there is clearly a need for novel, well defined, syntheticoxidized phospholipid derivatives exhibiting enhanced metabolicstability and efficient tolerizing immunogenicity in intravenous,intraperitoneal and mucosal administration.

Synthesis of Oxidized Phospholipids

Modification of phospholipids has been employed for a variety ofapplications. For example, phospholipids bearing lipid-soluble activecompounds may be incorporated into compositions for trans-dermal andtrans-membranal application (U.S. Pat. No. 5,985,292 to Fournerou etal.) and phospholipid derivatives can be incorporated into liposomes andbiovectors for drug delivery (see, for example, U.S. Pat. Nos. 6,261,597and 6,017,513 to Kurtz and Betbeder, et al., respectively, and U.S. Pat.No. 4,614,796). U.S. Pat. No. 5,660,855 discloses lipid constructs ofaminomannose derivatized cholesterol suitable for targeting smoothmuscle cells or tissue, formulated in liposomes. These formulations areaimed at reducing restenosis in arteries, using PTCA procedures. The useof liposomes for treating atherosclerosis has been further disclosed inWO 95/23592, to Hope and Rodrigueza, who teach pharmaceuticalcompositions of unilamellar liposomes that may contain phospholipids.The liposomes disclosed in WO 95/23592 are aimed at optimizingcholesterol efflux from atherosclerotic plaque and are typicallynon-oxidized phospholipids.

Modified phospholipid derivatives mimicking platelet activation factor(PAF) structure are known to be pharmaceutically active in variety ofdisorders and diseases, effecting such functions as vascularpermeability, blood pressure, heart function inhibition etc. It has beensuggested that one group of these derivatives may have anti cancerousactivity (U.S. Pat. No. 4,778,912 to Inoue at al.). However, thecompound disclosed in U.S. Pat. No. 4,778,912 possesses a much longerbridge between the phosphate and the tertiary amine moiety than in thephosphatidyl group and therefore is not expected to be immunologicallysimilar to Ox LDL. U.S. Pat. No. 4,329,302 teaches syntheticphosphoglycerides compounds—lysolechitin derivatives—that are usable inmediating platelet activation. While the compounds disclosed in U.S.Pat. No. 4,329,302 are either 1-O-alkyl ether or 1-O-fatty acylphosphoglycerides, it was found that small chain acylation oflysolechitin gave rise to compounds with platelet activating behaviour,as opposed to long-chain acylation, and that the 1-O-alkyl ether arebiologically superior to the corresponding 1-O-fatty acyl derivatives inmimicking PAF.

The structural effect of various phospholipids on the biologicalactivity thereof has also been investigated by Tokumura et al. (Journalof Pharmacology and Experimental Therapeutics. July 1981, Vol. 219,No. 1) and in U.S. Pat. No. 4,827,011 to Wissner et al., with respect tohypertension.

Another group of modified phospholipid ether derivatives has beendisclosed which was intended for chromatographic separation, but mighthave some physiological effect (CH Pat. No. 642,665 to Berchtold).

Oxidation of phospholipids occurs in vivo through the action of freeradicals and enzymatic reactions abundant in atheromatous plaque. Invitro, preparation of oxidized phospholipids usually involves simplechemical oxidation of a native LDL or LDL phospholipid component.Investigators studying the role of oxidized LDL have employed, forexample, ferrous ions and ascorbic acid (Itabe, H., et al., J. Biol.Chem. 1996; 271:33208-217) and copper sulfate (George, J. et al.,Atherosclerosis. 1998; 138:147-152; Ameli, S. et al., ArteriosclerosisThromb Vasc Biol 1996; 16:1074-79) to produce oxidized, or mildlyoxidized phospholipid molecules similar to those associated with plaquecomponents. Similarly prepared molecules have been shown to be identicalto auto-antigens associated with atherogenesis (Watson A. D. et al., J.Biol. Chem. 1997; 272:13597-607) and able to induce protectiveanti-atherogenic immune tolerance (U.S. patent application Ser. No.09/806,400 to Shoenfeld et al., filed Sep. 30, 1999) in mice. Likewise,Koike (U.S. Pat. No. 5,561,052) discloses a method of producing oxidizedlipids and phospholipids using copper sulfate and superoxide dismutaseto produce oxidized arachidonic or linoleic acids and oxidized LDL fordiagnostic use. Davies et al. (J. Biol. Chem. 2001, 276:16015) teach theuse of oxidized phospholipids as peroxisome proliferator-activatedreceptor agonists.

1-Palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC, seeExample I for a 2-D structural description) and derivatives thereof suchas 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) arerepresentative examples of mildly oxidized esterified phospholipids thathave been studied with respect to atherogenesis (see, for example,Boullier et al., J. Biol. Chem. 2000, 275:9163; Subbanagounder et al.,Circulation Research, 1999, pp. 311). The effect of different structuralanalogs that belong to this class of oxidized phospholipids has alsobeen studied (see, for example, Subbanagounder et al., Arterioscler.Thromb. Nasc. Biol. 2000, pp. 2248; Leitinger et al., Proc. Nat. Ac.Sci. 1999, 96:12010).

However, in vivo applications employing oxidized phospholipids preparedas above have the disadvantage of susceptibility to recognition, bindingand metabolism of the active component in the body, making dosage andstability after administration an important consideration.

Furthermore, the oxidation techniques employed are non-specific,yielding a variety of oxidized products, necessitating either furtherpurification or use of impure antigenic compounds. This is of evengreater concern with native LDL, even if purified.

Thus, there is a widely recognized need for, and it would be highlyadvantageous to have, a novel, synthetic oxidized phospholipid andimproved methods of synthesis and use thereof devoid of the abovelimitations.

SUMMARY OF THE INVENTION

According to the present invention there is provided a compound having aformula:

or pharmaceutically acceptable salts thereof, wherein:

-   (i) A₁ and A₂ are each independently selected from the group    consisting of CH₂ and C═O, at least one of A₁ and A₂ being CH₂;-   (ii) R₁ and R₂ are each independently selected from the group    consisting of an alkyl chain having 1-27 carbon atoms and

-   -   wherein X is an alkyl chain having 1-14 carbon atoms, Y is        selected from the group consisting of:

—OH, —H, alkyl, alkoxy, halogen, acetoxy and aromatic functional groups;and

-   -   Z is selected from the group consisting of:

whereas R₄ is an alkyl,

-   -   at least one of R₁ and R₂ being

as described

-   -   above; and

-   (iii) R₃ is selected from the group consisting of H, acyl, alkyl,    phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl    serine, phosphatidyl cardiolipin and phosphatidyl inisitol.

According to further features in the preferred embodiments of theinvention described below, R₃ is a non-phosphatidyl moeity, and as suchthe compound is a diglyceride.

According to still further features in the described preferredembodiments each of A₁ and A₂ is CH₂.

According to still further features in the described preferredembodiments R₁ is an alkyl chain having 1-27 carbon atoms and R₂ is

as described hereinabove.

According to another aspect of the present invention there is provided apharmaceutical composition for prevention and/or treatment ofatherosclerosis, cardiovascular disorders, cerebrovascular disorders,peripheral vascular disease, stenosis, restenosis and/orin-stent-stenosis in a subject in need thereof, the compositioncomprising, as an active ingredient, a therapeutically effective amountof the compound described hereinabove and a pharmaceutically acceptablecarrier.

According to further features in preferred embodiments of the inventiondescribed below, the pharmaceutical composition is packaged andidentified for use in the prevention and/or treatment of at least onedisorder selected from the group consisting of atherosclerosis,cardiovascular disorders, cerebrovascular disease, peripheral vasculardisorders, stenosis, restenosis and/or in-stent-stenosis.

According to yet another aspect of the present invention there isprovided a pharmaceutical composition for prevention and/or treatment ofan inflammatory disorder, an immune mediated disease, an autoimmunedisease and a proliferative disorder selected from the group consistingof aging, rheumatoid arthritis, juvenile rheumatoid arthritis,inflammatory bowl disease and cancer in a subject in need thereof,comprising, as an active ingredient, a therapeutically effective amountof the compound described hereinabove and a pharmaceutically acceptablecarrier.

According to further features in preferred embodiments of the inventiondescribed below, the pharmaceutical composition is packaged andidentified for use in the prevention and/or treatment of an inflammatorydisorder, an immune mediated disease, an autoimmune disease and aproliferative disorder selected from the group consisting of aging,rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory bowldisease and cancer.

According to yet further features in preferred embodiments of theinvention described below, each of the pharmaceutical compositionsdescribed above is designed for inducing tolerance to oxidized LDL viamucosal administration.

According to further features in preferred embodiments of the inventiondescribed below, each of the pharmaceutical compositions described aboveis designed for nasal, oral, subcutaneous or intra-peritonealadministration, alone or in combination with additional routes ofimmunomodulation.

According to still further features in preferred embodiments of theinvention described below, the compound reduces immune reactivity tooxidized LDL in the subject.

According to still further features in preferred embodiments of theinvention described below, each of the pharmaceutical compositionsdescribed above further comprises a therapeutically effective amount ofat least one additional compound selected from the group consisting ofHMG CoA reductase inhibitors (Statins) mucosal adjuvants,corticosteroids, anti-inflammatory compounds, analgesics, growthfactors, toxins, and additional tolerizing antigens.

According to still another aspect of the present invention there isprovided a pharmaceutical composition for prevention and/or treatment ofa disease, syndrome or condition selected from the group consisting ofatherosclerosis, cardiovascular disorders, cerebrovascular disorders,peripheral vascular disease, stenosis, restenosis and/orin-stent-stenosis in a subject in need thereof, comprising, as an activeingredient, a therapeutically effective amount of a synthetic LDLderivative, or pharmaceutically acceptable salts thereof the compositionfurther comprising a pharmaceutically acceptable carrier.

According to an additional aspect of the present invention there isprovided a method of prevention and/or treatment of atherosclerosis,cardiovascular disease, cerebrovascular disease, peripheral vasculardisease, stenosis, restenosis and/or in-stent-stenosis in a subject inneed thereof, the method comprising administering a therapeuticallyeffective amount of the compound of the present invention as describedhereinabove.

According to yet an additional aspect of the present invention there isprovided a method of prevention and/or treatment of an inflammatorydisorder, an immune mediated disease, an autoimmune disease and aproliferative disorder selected from the group consisting of aging,rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory bowldisease and cancer in a subject in need thereof, the method comprisingadministering a therapeutically effective amount of the compound of thepresent invention as described hereinabove.

According to yet further features in preferred embodiments of theinvention described below, the compound is administered via mucosaladministration.

According to further features in preferred embodiments of the inventiondescribed below, the administration of the compound is nasal, oral,subcutaneous or intra-peritoneal administration, alone or in combinationwith additional routes of immunomodulation.

According to still further features in preferred embodiments of theinvention described below, the administration of the compound reducesimmune reactivity to oxidized LDL in the subject.

According to further features in preferred embodiments of the inventiondescribed below, the compound is administered in addition to atherapeutically effective amount of at least one additional compoundselected from the group consisting of HMG CoA reductase inhibitors(Statins), mucosal adjuvants, corticosteroids, anti-inflammatorycompounds, analgetics, growth factors, toxins, and additional tolerizingantigens.

According to still further features in preferred embodiments of theinvention described below, preferred compounds that are usable in thecontext of the present invention include1-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphocholine (D-ALLE),3-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-1-phosphocholine (L-ALLE) andracemic mixtures thereof;1-hexadecyl-2-(5′-carboxy-butyl)-sn-glycero-3-phosphcholine (CI-201) andits corresponding acetals and any combination of the above.

According to yet a further aspect of the present invention there isprovided a method of synthesizing an oxidized phospholipid, the methodcomprising: (a) providing a phospholipid backbone including two fattyacid side chains, wherein at least one of the fatty acid side chains isa mono-unsaturated fatty acid; and (b) oxidizing the unsaturated bond ofthe mono-unsaturated fatty acid to thereby generate the oxidizedphospholipid.

According to further features in preferred embodiments of the inventiondescribed below the phospholipid backbone further includes a moietyselected from the group consisting of H, acyl, alkyl, phosphatidylcholine, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidylcardiolipin and phosphatidyl inositol.

According to still further features in preferred embodiments of theinvention described below the mono unsaturated fatty acid is C_(2-15.)

According to yet further features in preferred embodiments of theinvention described below the oxidized phospholipid is1-palmitoyl-2-oxovaleroyl-sn-glycero-3-phosphocholine, (POVPC), and themono-unsaturated fatty acid is 5-hexenoic acid.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing novel synthetic oxidized LDLderivatives and methods of inducing immune tolerance to oxidized LDLutilizing same, as well as a novel approach of synthesizing oxidized LDLderivatives.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 is a flow chart depicting the synthesis of 2,5′ Aldehyde lecitinether, 1-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphocholine (forD-ALLE) or 3-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-1-phosphocholine(for L-ALLE) (ALLE), according to the synthesis method of the presentinvention;

FIG. 2 is a flow chart depicting the synthesis of POVPC according to thepresent invention;

FIG. 3 is a graphic representation demonstrating inhibition of earlyatherogenesis in apoE-deficient mice by intra peritoneal immunizationwith mixed D- and L-isomers of ALLE. 5-7 week old apo-E knock out micewere immunized with 150 μg/mouse mixed D- or L-isomers of ALLE coupledto purified tuberculin protein derivative (ALLE L+D) (n=6), purifiedtuberculin protein derivative alone (PPD) (n=5) or unimmunized (CONTROL)(n=7). Atherogenesis is expressed as the area of atheromatous lesions inthe aortic sinus 4.5 weeks following the 4^(th) immunization;

FIG. 4 is a graphic representation demonstrating inhibition of earlyatherogenesis in apoE-knock out mice by oral tolerance induced byfeeding ALLE. 6-7.5 week old apo-E knock out mice were fed mixed D- andL-isomers of ALLE: 10 μg/mouse (ALLE L+D 10 μg) (n=11) or 1 mg/mouse(ALLE L+D 1 mg)(n=11); or PBS (CONTROL) (n=12) every other day for 5days. Atherogenesis is expressed as the area of atheromatous lesions inthe aortic sinus 8 weeks after the last feeding;

FIG. 5 is a graphic representation demonstrating inhibition of earlyatherogenesis in apoE-knock out mice by mucosal tolerance induced byoral feeding L-ALLE. 7-10 week old apo-E knock out mice were either fed1 mg/mouse L-ALLE every other day for 5 days (OT L-ALLE) (n=11) orintranasally administered with 10 μg/mouse L-ALLE every other day for 3days (NT L-ALLE)(n=11). Control mice were fed an identical volume (0.2ml) of PBS (PBS ORAL)(n=12). Atherogenesis is expressed as the area ofatheromatous lesions in the aortic sinus 8 weeks after the last oral ornasal exposure;

FIG. 6 is a graphic representation demonstrating suppression of immunereactivity to atheroslerotic plaque antigens induced by oral feedingwith the synthetic oxidized phospholipids L-ALLE and POVPC. 6 week oldmale apo-E mice were fed either 1 mg/mouse L-ALLE (L-ALLE) (n=2) orPOVPC(POVPC) (n=3) in 0.2 ml PBS; or PBS alone (CONTROL) (n=3) everyother day for 5 days. One week following the last feeding the mice wereimmunized with a single subcutaneous injection of 50 μg Human oxidizedLDL antigen. 7 days later T-cells from inguinal lymph node were preparedas described in Materials and Methods section that follows, and exposedto the sensitizing Human ox-LDL antigen for in-vitro assessment ofproliferation. Proliferation, indicating immune reactivity, is expressedas the ratio between incorporation of labeled thymidine into theT-cell's DNA in the presence and absence of human ox-LDL antigen(stimulation index, S.I.).

FIG. 7 is a graphic representation demonstrating inhibition ofprogression of late-stage atherogenesis in apoE-knock out mice by oraltolerance induced with the synthetic oxidized phospholipids D-ALLE,L-ALLE or POVPC. 24.5 week old apo-E knock out mice were fed 1 mg/mouseL-ALLE (L-ALLE) (n=11), D-ALLE (D-ALLE) (n=9) or POVPC (POVPC) (n=10)every other day for 5 days, at 4 week intervals over a 12 week period.Control mice were fed an identical volume (0.2 ml) and regimen of PBS(CONTROL) (n=10). Atherogenesis is expressed as the area of atheromatouslesions in the aortic sinus 12 weeks after the first feeding, ascompared to the lesion scores of untreated 24.5 week old mice beforefeeding (Time 0);

FIG. 8 is a graphic representation demonstrating reduction oftriglyceride content of VLDL in apoE-knock out mice induced by feedingsynthetic oxidized phospholipids D-ALLE, L-ALLE or POVPC. 24.5 week oldapo-E mice were fed 1 mg/mouse L-ALLE (triangle) (n=11), D-ALLE(inverted triangle) (n=9) or POVPC (square) (n=10) every other day for 5days, at 4 week intervals over a 12 week period. Control mice were fedan identical volume (0.2 ml) and regimen of PBS (circle) (n=10).Triglyceride content (Tg, mg/ml) was measured 9 weeks from t=0, byenzymatic calorimetric method in the VLDL fractions following separationof pooled blood samples on FPLC, as described in the materials andmethods section that follows;

FIG. 9 is a graphic representation demonstrating reduction ofcholesterol content of VLDL in apoE-knock out mice induced by feedingsynthetic oxidized phospholipids D-ALLE, L-ALLE or POVPC. 24.5 week oldapo-E mice were fed 1 mg/mouse L-ALLE (triangle) (n=11), D-ALLE(inverted triangle) (n=9) or POVPC (square) (n=10) every other day for 5days, at 4 week intervals over a 12 week period. Control mice were fedan identical volume (0.2 ml) and regimen of PBS (circle) (n=10).Cholesterol content (Cholesterol, mg/ml) was measured 9 weeks from t=0,by enzymatic calorimetric method in the VLDL fractions followingseparation of pooled blood samples on FPLC, as described in thematerials and methods section that follows;

FIG. 10 presents 2D structural descriptions of1-Hexadecyl-2-(5′-Carboxy-butyl)-sn-glycero-3-phosphcholine (IC-201,Compound I),1-Hexadecyl-2-(5′,5′-Dimethoxy-pentyloxy)-sn-glycero-3-phosphcholine(Compound IIa) and1-Hexadecyl-2-(5′,5′-Diethoxy-pentyloxy)-sn-glycero-3-phosphcholine(Compound IIb);

FIG. 11 is a graphic representation demonstrating inhibition of earlyatherogenesis in apoE-knock out mice by oral tolerance induced byfeeding CI-201. 12 week old apo-E mice were fed CI-201: 0.025 mg/mouse(n=14); or 0.2 ml PBS (CONTROL) (n=15) every day for 8 weeks (5 times aweek). Atherogenesis is expressed as the area of atheromatous lesions inthe aortic sinus. Atherosclerosis is expressed as the area ofatheromatous lesion in the aortic sinus 11 weeks after the firstfeeding; and

FIGS. 12 a-d present photographs demonstrating the cytokine expressionlevels in the aorta of mice treated with ALLE, CI-201, its ethyl acetalderivative (Et-acetal), its methyl acetal derivative (Me-acetal), oxLDLor PBS. Particularly, FIGS. 12 a and 12 b present the elevation of IL-10expression level in the aorta of mice treated with ALLE, CI-201,Et-acetal, Me-acetal and oxLDL as compared with non-treated mice (PBS)and the reduced IFN-gamma expression levels in aortas from mice treatedwith ALLE, CI-201, Me-acetal and oxLDL as compared with PBS treatedmice, and FIGS. 12 c and 12 d present the reduced IL-12 expression inmice treated with ALLE, CI-201 and Et-acetal as compared with PBStreated group. 10-12 weeks old ApoE knock out mice were fed 1mg/mouse/0.2 ml of the tested antigen (ALLE, CI-201, Et-acetal,Me-acetal) or 0.1 mg/mouse/0.2 ml oxLDL or administered with 0.2 ml PBS.Oral administrations took place 5 times every other day and the cytokineexpression was evaluated 8 weeks after the last oral administration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of methods and compositions employing syntheticoxidized phospholipids effective in inducing mucosal tolerance andinhibiting inflammatory processes contributing to atheromatous vasculardisease and sequalae.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details set forth in the following description or exemplified bythe Examples. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

Experimental and clinical evidence indicates a causative role foroxidized LDL and LDL components in the etiology of the excessiveinflammatory response in atherosclerosis. Both cellular and humoralimmune reactivity to plaque related oxidized LDL have been demonstrated,suggesting an important anti-oxidized LDL auto-immune component inatherogenesis. Thus, oxidized LDL and components thereof, have been thetargets of numerous therapies for prevention and treatment of heartdisease, cerebral-vascular disease and peripheral vascular disease.

Although the prior art teaches that oral administration of LDL canresult in 30% reduction in atherogenesis, such a protective effect wasobserved following administration of a crude antigen preparationconsisting of centrifuged, filtered and purified human serum LDL whichhad been subjected to a lengthy oxidation process with Cu⁺⁺. Althoughsignificant inhibition of atherogenesis was achieved, presumably viaoral tolerance, no identification of specific lipid antigens orimmunogenic LDL components was made.

Another obstacle encountered was the inherent instability of the crudeoxidized LDL in vivo, due to enzymatic activity and uptake of oxidizedLDL by the liver and cellular immune mechanisms. Such an inherentinstability is also associated with in vivo applications that utilizeother oxidized LDL derivatives, such as POVPC and PGPC (describedhereinabove).

In view of the growing need for oxidized LDL derivatives devoid of theseinherent instability, and as the presently known studies that relate toatherogenesis involve synthetic oxidized LDL derivatives that typicallyinclude esterified phospholipids such as 1,2-O-fatty acylphosphoglycerides, the present inventors have envisioned that syntheticoxidized LDL derivatives which include etherified phospholipids canserve as stable, novel agents for inducing immune tolerance to oxidizedLDL.

While reducing the present invention to practice, the present inventorshave synthesized a novel class of well-defined synthetic oxidized LDLderivatives (etherified phospholipids) and have uncovered thatadministration of such oxidized LDL derivatives can induce immunetolerance to oxidized LDL and thus inhibit atherogenesis, while avoidingthe abovementioned limitations.

Hence, according to one aspect of the present invention there isprovided a compound having the general formula:

or pharmaceutically acceptable salts thereof wherein:

-   -   (i) A₁ and A₂ are each independently selected from the group        consisting of CH₂ and C═O, at least one of A₁ and A₂ being CH₂;    -   (ii) R₁ and R₂ are each independently selected from the group        consisting of an alkyl chain having 1-27 carbon atoms and

wherein X is an alkyl chain having 1-24 carbon atoms, Y is selected fromthe group consisting of:

—OH, —H, alkyl, alkoxy halogen, acetoxy and aromatic functional groups;and

Z is selected from the group consisting of:

whereas R₄ is an alkyl,

at least one of R₁ and R₂ being

-   -   (iii) R₃ is selected from the group consisting of H, acyl,        alkyl, phosphatidyl choline, phosphatidyl ethanolamine,        phosphatidyl serine, phosphatidyl cardiolipin and phosphatidyl        inisitol.

In one embodiment of the present invention, one of A₁ and A₂ is CH₂ andhence the compound of the present invention is a mono-etherifiedphospholipid having an O-fatty acyl component. However, in a preferredembodiment of the present invention each of A₁ and A₂ is CH₂ and hencethe compound of the present invention is a dietherified phospholipid.Such dietherified phospholipids do not include the inherent instableO-fatty acyl component and are hence characterized by improved in vivostability, particularly as compared with the presently known syntheticoxidized pholpholipids (e.g., POVPC and PGPC).

As is described in the formula hereinabove, at least one of R₁ and R₂ isan oxidized alkyl chain. However, since in naturally occurring oxidizedLDL derivatives the oxidized alkyl chain is typically located at thesecond position, and since it has been demonstrated that the biologicalactivity of several phospholipids directly depends on the structurethereof (see the Background section for a detailed discussion), in apreferred embodiment of the present invention R₁ is a non-oxidized alkylchain while R₂ is an oxidized alkyl chain.

As is further described in the formula hereinabove, the oxidized alkylchain include oxidized functional groups such as

One example of a novel etherified oxidized phospholipid of the presentinvention is 2,5′-Aldehyde Lecithin Ether (ALLE):1-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphocholine (D-ALLE),3-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-1-phosphocholine (L-ALLE)],and the racemic mixture thereof, the synthesis and use of which arefurther detailed in the Examples section which follows.

However, as aldehydes are known as unstable compounds, which tend to beeasily oxidized, preferred examples of novel etherified oxidizedphospholipids according to the present invention include the acidderivative 1-Hexadecyl-2-(5′-Carboxy-butyl)-sn-glycero-3-phosphcholine(also referred to hereinafter as IC-201), and its corresponding acetals1-Hexadecyl-2-(5′,5′-Dimethoxy-pentyloxy)-sn-glycero-3-phosphcholine and1-Hexadecyl-2-(5′,5′-Diethoxy-pentyloxy)-sn-glycero-3-phosphcholine (seeFIG. 10 for 2-D structural formulas), the synthesis and use of which arealso further detailed in the Examples section which follows.

In this respect it should be noted that carboxylic acid derivatives ofoxidized etherified phospholipids have been disclosed in CH Pat. No.642,665. However, CH Pat. No. 642,665 teaches etherified phospholipidsin which the carboxylic acid is located at the first position of thephospholipid backbone and hence, as is discussed hereinabove, it isassumed that such compounds would not be as biologically active as thecorresponding compounds bearing the carboxylic acid group at the secondposition of the phospholipid backbone. Studies on the structure-activityrelationship with respect to the location of the oxidized alkyl chain inthe phospholipid backbone, which are aimed at more clearly demonstratingthe superior activity of etherified oxidized phospholipids having anoxidized alkyl chain at the second position of the phospholipidbackbone, are currently being conducted by the present inventors.

As is described in the formula hereinabove, R₃ is either a phosphatidylmoiety (e.g., phosphatidyl choline, phosphatidyl ethanolamine, etc.) ora non-phosphatidyl moiety (e.g., acyl or alkyl). When R₃ is anon-phosphatidyl moiety, the resultant compound is not a phospholipid,rather a diglyceride compound. Such diglyceride compounds retain similarstructure characteristics and as such in all probability would possesantigenicity and immune tolerizing activity. Thus, these compounds canalso be used in prevention and/or treatment of atherosclerosis relateddisorders, and employed and applied similarly to the oxidizedphospholipid derivatives described herein.

As is described in the Examples section that follows, the compounds ofthe present invention have been found to induce immune tolerance tooxidized LDL.

Thus, according to another aspect of the present invention there isprovided a method of inducing immune tolerance to oxidized LDL in asubject such as a human being. Such immune tolerance can be used in theprevention and/or treatment of disorders associated with plaqueformation, including but not limited to atherosclerosis, atheroscleroticcardiovascular disease, cerebrovascular disease, peripheral vasculardisease, stenosis, restenosis and in-stent-stenosis. Some non-limitingexamples of atherosclerotic cardiovascular disease are myocardialinfarction, coronary arterial disease, acute coronary syndromes,congestive heart failure, angina pectoris and myocardial ischemia. Somenon-limiting examples of peripheral vascular disease are gangrene,diabetic vasculopathy, ischemic bowel disease, thrombosis, diabeticretinopathy and diabetic nephropathy. Non-limiting examples ofcerebrovascular disease are stroke, cerebrovascular inflammation,cerebral hemorrhage and vertebral arterial insufficiency. Stenosis isocclusive disease of the vasculature, commonly caused by atheromatousplaque and enhanced platelet activity, most critically affecting thecoronary vasculature. Restenosis is the progressive re-occlusion oftenfollowing reduction of occlusions in stenotic vasculature. In caseswhere patency of the vasculature requires the mechanical support of astent, in-stent-stenosis may occur, re-occluding the treated vessel.

As is further detailed in the Examples section which follows, themethod, according to this aspect of the present invention is effected byadministering to the subject a therapeutically effective amount of thesynthetic etherified oxidized phospholipids of the present inventiondescribed hereinabove.

Recently, phospholipids and phospholipid metabolites have been clearlyimplicated in the pathogenesis, and therefore potential treatment, ofadditional, non-atherosclerosis-related diseases. Such diseases andsyndromes include, for example, oxidative stress of aging (Onorato J M,et al, Annal N Y Acad Sci 1998 Nov. 20; 854:277-90), rheumatoidarthritis (RA) (Paimela L, et al. Ann Rheum Dis 1996 August;55(8):558-9), juvenile rheumatoid arthritis (Savolainen A, et al, 1995;24(4):209-11), inflammatory bowel disease (IBD) (Sawai T, et al, PediatrSurg Int 2001 May; 17(4):269-74) and renal cancer (Noguchi S, et al,Biochem Biophys Res Commun 1992 Jan. 31; 182(2):544-50). Thus, thecompounds of the present invention can also be used in a method forprevention and/or treatment of non-atherosclerosis related diseases suchas infalammatory disorders, immune mediated diseases, autoimmunediseases and proliferative disorders. Non-limiting examples of suchdisorders and diseases include aging, RA, juvenile RA, IBD and cancer,as is described hereinabove.

While the etherified oxidized phospholipids of the present invention canbe synthesized using modifications of prior art approaches, whilereducing the present invention to practice, the present inventors haveuncovered a novel method for synthesizing such compounds, which can alsobe utilized for synthesizing other classes of oxidized phospholipids(e.g., esterified oxidized phospholipids).

Thus, according to another aspect of the present invention there isprovided a method of synthesizing an oxidized phospholipid. The methodis effected by first providing a phospholipid backbone including twofatty acid side chains, at least one of the fatty acid side chains beinga mono-unsaturated fatty acid (preferably a C₂₋₁₅ fatty acid), followedby oxidizing the unsaturated bond of the mono-unsaturated fatty acid,thereby generating the oxidized phospholipid.

The oxidation of the unsaturated bond can be performed using knownoxidizing agents such as, for example, potassium meta periodate.

Examples of phospholipid backbones suitable for synthesis of, forexample, an esterified oxidized phospholipid according to the teachingsof the present invention include, but are not limited to lecithin, whichincludes two O-fatty acyl side chains, and lysolecithin which includes asingle O-fatty acyl side chain and as such must undergo an additionalsynthesis step of adding an additional fatty acid side chain prior tooxidation.

The novel synthesis method of the present invention can be used, forexample, for synthesizing the esterified phospholipid POVPC, which, asis detailed in the Background section hereinabove, is known to beassociated with atherogenesis. When utilized to synthesize POVPC, thephospholipid backbone includes 5-hexenoic acid as the mono-unsaturatedfatty acid side chain.

The novel synthesis approach of the present invention provides severaladvantages over prior art synthesis approaches. In this syntheticmethod, a defined mono unsaturated acid of desired length and structureis reacted with a molecule having lysolecithin backbone to givemonounsaturated phospholipids, which is then oxidized at the desiredunsaturated double bond.

The advantages of such a novel approach is in its specificity andsimplicity. Oxidizing mono-unsaturated phospholipids having lecithinbackbone results in a single, desired specific product and thereforecommercial product work up and purification is made much more efficient.

Such a reaction provides specific, desired oxidized phospholipids,traversing the need to perform complicated separations and purification.

Furthermore, using this method it is possible to design and synthesizeoxidized phospholipids by oxidation of mono-unsaturated phospholipidswith a double bond at the end of the chain, enabling the use ofsubstantially short unsaturated acid chains in the synthetic process.Such mono-unsaturated short acid chains are relatively inexpensive, andthus reducing the costs associated with synthesis. As such, thesynthesis method of the present invention could therefore beconveniently adapted for large-scale manufacturing processes.

A detailed description of synthesis of etherified and esterifiedoxidized phospholipids according to the teachings of the presentinvention is provided in the Examples section which follows.

The immune tolerance inducing compounds described herein can be utilizedin the therapeutic applications described hereinabove, by beingadministered per se, or in a pharmaceutical composition where it ismixed with suitable carriers or excipients.

Thus, according to another aspect of the present invention, there areprovided pharmaceutical compositions for prevention and/or treatment ofatherosclerosis, cardiovascular disorders, cerebrovascular disorders,peripheral vascular disease, stenosis, restenosis and/orin-stent-stenosis in a subject in need thereof. The pharmaceuticalcompositions according to this aspect of the present invention comprise,as an active ingredient, a therapeutically effective amount of theetherified oxidized phospholipid of the present invention or any othersynthetic oxidized LDL derivative and a pharmaceutically acceptablecarrier.

The pharmaceutical compositions of the present invention can further beused for prevention and/or treatment of inflammatory disorders, immunemediated diseases, autoimmune diseases and proliferative disorders suchas, but not limited to, aging, RA, juvenile RA, IBD and cancer.

As used herein a “pharmaceutical composition” refers to a preparation ofone or more of the active ingredients described herein with otherchemical components such as physiologically suitable carriers andexcipients. The purpose of a pharmaceutical composition is to facilitateadministration of a compound to an organism.

Herein the term “active ingredient” refers to the compounds (e.g., ALLEand CI-201) accountable for the biological effect.

Hereinafter, the phrases “physiologically acceptable carrier” and“pharmaceutically acceptable carrier” which may be interchangeably usedrefer to a carrier or a diluent that does not cause significantirritation to an organism and does not abrogate the biological activityand properties of the administered compound. An adjuvant is includedunder these phrases.

Herein the term “excipient” refers to an inert substance added to apharmaceutical composition to further facilitate administration of anactive ingredient. Examples, without limitation, of excipients includecalcium carbonate, calcium phosphate, various sugars and types ofstarch, cellulose derivatives, gelatin, vegetable oils and polyethyleneglycols.

Techniques for formulation and administration of drugs may be found in“Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa.,latest edition, which is incorporated herein by reference.

Suitable routes of administration may, for example, include oral,rectal, transmucosal, especially transnasal, intestinal or parenteraldelivery, including intramuscular, subcutaneous and intramedullaryinjections as well as intrathecal, direct intraventricular, intravenous,inrtaperitoneal, intranasal, or intraocular injections.

Alternately, one may administer the pharmaceutical composition in alocal rather than systemic manner, for example, via injection of thepharmaceutical composition directly into a tissue region of a patient.

In a preferred embodiment of the present invention, the pharmaceuticalcompositions are designed for inducing tolerance to Ox LDL via mucosaladministration.

Further preferably, the pharmaceutical compositions of the presentinvention are designed for nasal, oral or intraperitonealadministration, as is detailed hereinafter.

Pharmaceutical compositions of the present invention may be manufacturedby processes well known in the art, e.g., by means of conventionalmixing, dissolving, granulating, dragee-making, levigating, emulsifying,encapsulating, entrapping or lyophilizing processes.

Pharmaceutical compositions for use in accordance with the presentinvention thus may be formulated in conventional manner using one ormore physiologically acceptable carriers comprising excipients andauxiliaries, which facilitate processing of the active ingredients intopreparations which, can be used pharmaceutically. Proper formulation isdependent upon the route of administration chosen.

For injection, the active ingredients of the pharmaceutical compositionmay be formulated in aqueous solutions, preferably in physiologicallycompatible buffers such as Hank's solution, Ringer's solution, orphysiological salt buffer. For transmucosal administration, penetrantsappropriate to the barrier to be permeated are used in the formulation.Such penetrants are generally known in the art.

For oral administration, the pharmaceutical composition can beformulated readily by combining the active compounds withpharmaceutically acceptable carriers well known in the art. Suchcarriers enable the pharmaceutical composition to be formulated astablets, pills, dragees, capsules, liquids, gels, syrups, slurries,suspensions, and the like, for oral ingestion by a patient.Pharmacological preparations for oral use can be made using a solidexcipient, optionally grinding the resulting mixture, and processing themixture of granules, after adding suitable auxiliaries if desired, toobtain tablets or dragee cores. Suitable excipients are, in particular,fillers such as sugars, including lactose, sucrose, mannitol, orsorbitol; cellulose preparations such as, for example, maize starch,wheat starch, rice starch, potato starch, gelatin, gum tragacanth,methyl cellulose, hydroxypropylmethyl-cellulose, sodiumcarbomethylcellulose; and/or physiologically acceptable polymers such aspolyvinylpyrrolidone (PVP). If desired, disintegrating agents may beadded, such as cross-linked polyvinyl pyrrolidone, agar, or alginic acidor a salt thereof such as sodium alginate.

Dragee cores are provided with suitable coatings. For this purpose,concentrated sugar solutions may be used which may optionally containgum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethyleneglycol, titanium dioxide, lacquer solutions and suitable organicsolvents or solvent mixtures. Dyestuffs or pigments may be added to thetablets or dragee coatings for identification or to characterizedifferent combinations of active compound doses.

Pharmaceutical compositions which can be used orally, include push-fitcapsules made of gelatin as well as soft, sealed capsules made ofgelatin and a plasticizer, such as glycerol or sorbitol. The push-fitcapsules may contain the active ingredients in admixture with fillersuch as lactose, binders such as starches, lubricants such as talc ormagnesium stearate and, optionally, stabilizers. In soft capsules, theactive ingredients may be dissolved or suspended in suitable liquids,such as fatty oils, liquid paraffin, or liquid polyethylene glycols. Inaddition, stabilizers may be added. All formulations for oraladministration should be in dosages suitable for the chosen route ofadministration.

For buccal administration, the compositions may take the form of tabletsor lozenges formulated in conventional manner.

For administration by nasal inhalation, the active ingredients for useaccording to the present invention are conveniently delivered in theform of an aerosol spray presentation from a pressurized pack or anebulizer with the use of a suitable propellant, e.g.,dichlorodifluoromethane, trichlorofluoromethane,dichloro-tetrafluoroethane or carbon dioxide. In the case of apressurized aerosol, the dosage unit may be determined by providing avalve to deliver a metered amount. Capsules and cartridges of, e.g.,gelatin for use in a dispenser may be formulated containing a powder mixof the compound and a suitable powder base such as lactose or starch.

The pharmaceutical composition described herein may be formulated forparenteral administration, e.g., by bolus injection or continuesinfusion. Formulations for injection may be presented in unit dosageform, e.g., in ampoules or in multidose containers with optionally, anadded preservative. The compositions may be suspensions, solutions oremulsions in oily or aqueous vehicles, and may contain formulatoryagents such as suspending, stabilizing and/or dispersing agents.

Pharmaceutical compositions for parenteral administration includeaqueous solutions of the active preparation in water-soluble form.Additionally, suspensions of the active ingredients may be prepared asappropriate oily or water based injection suspensions. Suitablelipophilic solvents or vehicles include fatty oils such as sesame oil,or synthetic fatty acids esters such as ethyl oleate, triglycerides orliposomes. Aqueous injection suspensions may contain substances, whichincrease the viscosity of the suspension, such as sodium carboxymethylcellulose, sorbitol or dextran. Optionally, the suspension may alsocontain suitable stabilizers or agents which increase the solubility ofthe active ingredients to allow for the preparation of highlyconcentrated solutions.

Alternatively, the active ingredient may be in powder form forconstitution with a suitable vehicle, e.g., sterile, pyrogen-free waterbased solution, before use.

The pharmaceutical composition of the present invention may also beformulated in rectal compositions such as suppositories or retentionenemas, using, e.g., conventional suppository bases such as cocoa butteror other glycerides.

Pharmaceutical compositions suitable for use in context of the presentinvention include compositions wherein the active ingredients arecontained in an amount effective to achieve the intended purpose. Morespecifically, a therapeutically effective amount means an amount ofactive ingredients effective to prevent, alleviate or amelioratesymptoms of a disorder (e.g., atherosclerosis) or prolong the survivalof the subject being treated.

Determination of a therapeutically effective amount is well within thecapability of those skilled in the art, especially in light of thedetailed disclosure provided herein.

For any preparation used in the methods of the invention, thetherapeutically effective amount or dose can be estimated initially fromin vitro and cell culture assays. For example, a dose can be formulatedin animal models to achieve a desired concentration or titer. Suchinformation can be used to more accurately determine useful doses inhumans.

Toxicity and therapeutic efficacy of the active ingredients describedherein can be determined by standard pharmaceutical procedures in vitro,in cell cultures or experimental animals. The data obtained from thesein vitro and cell culture assays and animal studies can be used informulating a range of dosage for use in human. The dosage may varydepending upon the dosage form employed and the route of administrationutilized. The exact formulation, route of administration and dosage canbe chosen by the individual physician in view of the patient'scondition. (See e.g., Fingi, et al., 1975, in “The Pharmacological Basisof Therapeutics”, Ch. 1 p. 1).

Dosage amount and interval may be adjusted individually to provideplasma or brain levels of the active ingredient are sufficient to induceor suppress angiogenesis (minimal effective concentration, MEC). The MECwill vary for each preparation, but can be estimated from in vitro data.Dosages necessary to achieve the MEC will depend on individualcharacteristics and route of administration. Detection assays can beused to determine plasma concentrations.

Depending on the severity and responsiveness of the condition to betreated, dosing can be of a single or a plurality of administrations,with course of treatment lasting from several days to several weeks oruntil cure is effected or diminution of the disease state is achieved.

The amount of a composition to be administered will, of course, bedependent on the subject being treated, the severity of the affliction,the manner of administration, the judgment of the prescribing physician,etc.

Compositions of the present invention may, if desired, be presented in apack or dispenser device, such as an FDA approved kit, which may containone or more unit dosage forms containing the active ingredient. The packmay, for example, comprise metal or plastic foil, such as a blisterpack. The pack or dispenser device may be accompanied by instructionsfor administration. The pack or dispenser may also be accommodated by anotice associated with the container in a form prescribed by agovernmental agency regulating the manufacture, use or sale ofpharmaceuticals, which notice is reflective of approval by the agency ofthe form of the compositions or human or veterinary administration. Suchnotice, for example, may be of labeling approved by the U.S. Food andDrug Administration for prescription drugs or of an approved productinsert. Compositions comprising a preparation of the inventionformulated in a compatible pharmaceutical carrier may also be prepared,placed in an appropriate container, and labeled for treatment of anindicated condition, as is further detailed above.

The present invention illustrates for the first time that syntheticderivatives of oxidized phospholipids, etherified oxidized phospholipidsin particular, can be used to prevent and treat atherosclerosis in asubject, while being devoid of limitations inherent to treatmentsutilizing biologically derived forms of oxidized LDL or other classes ofsynthetic derivatives of oxidized LDL.

The present invention also provides a novel approach for synthesizingoxidized phopholipids. The present invention also provides noveloxidized phospholipid ethers, utilizable for treatment ofatherosclerosis and related disorders, as well as other inflammatory andimmune related disorders and diseases.

Additional objects, advantages, and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting. Additionally, each of the various embodiments and aspects ofthe present invention as delineated hereinabove and as claimed in theclaims section below finds experimental support in the followingexamples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions, illustrate the invention in a non limiting fashion.

Generally, the nomenclature used herein and the laboratory proceduresutilized in the present invention include biochemical and immunologicaltechniques. Such techniques are thoroughly explained in the literature.See, for example, “Cell Biology: A Laboratory Handbook”, Volumes I-IIICellis, J. E., ed. (1994); “Current Protocols in Immunology” VolumesI-III Coligan J. E., ed. (1994); Stites et al. (eds), “Basic andClinical Immunology” (8th Edition), Appleton & Lange, Norwalk, Conn.(1994); Mishell and Shiigi (eds), “Selected Methods in CellularImmunology”, W. H. Freeman and Co., New York (1980); availableimmunoassays are extensively described in the patent and scientificliterature, see, for example, U.S. Pat. Nos. 3,791,932; 3,839,153;3,850,752; 3,850,578; 3,853,987; 3,867,517; 3,879,262; 3,901,654;3,935,074; 3,984,533; 3,996,345; 4,034,074; 4,098,876; 4,879,219;5,011,771 and 5,281,521; and “Methods in Enzymology” Vol. 1-317,Academic Press; Marshak et al., all of which are incorporated byreference as if fully set forth herein. Other general references areprovided throughout this document. The procedures therein are believedto be well known in the art and are provided for the convenience of thereader. All the information contained therein is incorporated herein byreference.

Materials and General Methods

Animals:

-   Apo-E knock out mice used in our experiments are from the    atherosclerosis prone strain C57BL/6J-Apoe^(tm1unc). Mice homozygous    for the Apoe^(tm1unc) mutations show a marked increase in total    plasma cholesterol levels which is unaffected by age or sex. Fatty    streaks in the proximal aorta are found at 3 months of age. The    lesions increase with age and progress to lesions with less lipid    but more elongated cells, typical of a more advanced stage of    pre-atheroscierotic lesion.

Strain Development: The Apoe^(tm1unc) mutant strain was developed in thelaboratory of Dr. Nobuyo Maeda at University of North Carolina at ChapelHill. The 129-derived E14Tg2a ES cell line was used. The plasmid used isdesignated as pNMC109 and the founder line is T-89. The C57BL/6J strainwas produced by backcrossing the Apoe^(tm1unc) mutation 10 times toC57BL/6J mice [11,12].

The mice were maintained at the Sheba Hospital Animal Facility(Tel-Hashomer, Israel) on a 12-hour light/dark cycle, at 22-24° C. andfed a normal fat diet of laboratory chow (Purina Rodent Laboratory ChowNo. 5001) containing 0.027% cholesterol, approximately 4.5% total fat,and water, ad libitum.

Immunization:

I. Intraperitioneal immunization with ALLE: The phospholipid etheranalog (ALLE D+L) was coupled to purified protein derivative fromtuberculin (PPD). The stock solution of ALLE (D+L) was dissolved inethanol (99 mg/ml). 5 mg ALLE (D+L), (60.5□l from stock solution) wasdiluted to 5 mg/ml with 0.25M phosphate buffer, pH 7.2, by stirring onice. 1.5 mg of D- and L-ALLE in 300 □l of phosphate buffer were added to0.6 mg PPD dissolved in 300 □l of phosphate buffer.1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimid-HCl (5 mg; Sigma, St.Louis, Mo.) dissolved in 50 □l of water was added by stirring at 4° for20 min. The remaining active sites were blocked with 100 □l of 1Mglycine. Coupled compounds were dialyzed against phosphate-bufferedsaline (PBS), adjusted to 3 ml with PBS and stored at 4° C. Immunizationwith 0.3 ml (15 □g) antigen per mouse was performed intraperitoneally 4times every 2 weeks.

II. Subcutaneous immunization with Human oxidized LDL: Human oxidizedLDL was prepared from human plasma pool (d-1.019 to 1.063 gram/ml byultracentrifugation) and was Cu-oxidized overnight (by adding 15 □l 1 mMCuSO₄ to each ml of LDL previously diluted to 1 mg/ml concentration).The oxidized LDL was dialyzed against PBS and filtrated. Forimmunization, oxidized LDL was dissolved in PBS and mixed with equalvolumes of Freund's incomplete adjuvant. Immunizations were performed bysingle subcutaneous injection of 50 □g antigen/mouse in 0.2 ml volume.One to three days following the last oral administration the micereceived one immunization, and were sacrificed 7-10 days postimmunization.

Cholesterol Level Determination: At the completion of the experiment,1-1.5 ml of blood was obtained by cardiac puncture, 1000 U/ml heparinwas added to each sample and total plasma cholesterol levels weredetermined using an automated enzymatic technique (Boehringer Mannheim,Germany).

FPLC Analysis: Fast Protein Liquid Chromatography analysis ofcholesterol and lipid content of lipoproteins was performed usingSuperose 6 HR 10/30 column (Amersham Pharmacia Biotech, Inc, Peapack,N.J.) on a FPLC system (Pharmacia LKB. FRAC-200, Pharmacia, Peapack,N.J.). A minimum sample volume of 300 □l (blood pooled from 3 mice wasdiluted 1:2 and filtered before loading) was required in the samplingvial for the automatic sampler to completely fill the 200 □l sampleloop. Fractions 10-40 were collected, each fraction contained 0.5 ml. A250 □l sample from each fraction was mixed with freshly preparedcholesterol reagent or triglyceride reagent respectively, incubated for5 minutes at 37° C. and assayed spectrophotometrically at 500 nm.

Assessment of Atherosclerosis: Quantification of atherosclerotic fattystreak lesions was done by calculating the lesion size in the aorticsinus as previously described [16] and by calculating the lesion size inthe aorta. Briefly, after perfusion with saline Tris EDTA, the heart andthe aorta were removed from the animals and the peripheral fat cleanedcarefully. The upper section of the heart was embedded in OCT medium(10.24% w/w polyvinyl alcohol; 4.26% w/w polyethylene glycol; 85.50% w/wnonreactive ingredients) and frozen. Every other section (10 μm thick)throughout the aortic sinus (400 μm) was taken for analysis. The distalportion of the aortic sinus was recognized by the three valve cusps thatare the junctions of the aorta to the heart. Sections were evaluated forfatty streak lesions after staining with oil-red O. Lesion areas persection were scored on a grid [17] by an observer counting unidentified,numbered specimens. The aorta was dissected from the heart andsurrounding adventitious tissue was removed. Fixation of the aorta andSudan staining of the vessels were performed as previously described[21].

Proliferation assays: Mice were fed with ALLE, POVPC or PBS as describedfor assessment of atherosclerosis, and then immunized one day followingthe last feeding with oxidized LDL prepared from purified human LDL asdescribed above.

Proliferation was assayed eight days after immunization with theoxidized LDL as follows: Spleens or lymph nodes were prepared by meshingthe tissues on 100 mesh screens. (Lymph nodes where immunization wasperformed, and spleens where no immunization performed). Red blood cellswere lysed with cold sterile double distilled water (6 ml) for 30seconds and 2 ml of NaCl 3.5% were added. Incomplete medium was added(10 ml), cells were centrifuge for 7 minutes at 1,700 rpm, resuspendedin RPMI medium and counted in a haemocytometer at 1:20 dilution (10 □lcells+190 □l Trypan Blue). Proliferation was measured by theincorporation of [³H]-Thymidine into DNA in triplicate samples of 100 □lof the packed cells (2.5×10⁶ cells/ml) in a 96 well microtiter plate.Triplicate samples of oxidized LDL (0-10 □g/ml, 100 □l/well) were added,cells incubated for 72 hours (37° C., 5% CO₂ and about 98% humidity) and10 □l ³[H]-Thymidine (0.5 □Ci/well) were added. After an additional dayof incubation the cells were harvested and transferred to glass fiberfilters using a cell harvester (Brandel) and counted using □-counter(Lumitron). For assay of cytokines the supernatant was collected withoutadding ³[H]-Thymidine and assayed by ELISA.

A separate group of mice were fed with ALLE or PBS and immunized withoxidized LDL as described above, one day following the last fed dose.Draining inguinal lymph nodes (taken 8 days after immunization) werecollected from 3 mice from each of the groups, for the proliferationstudies. 1×10⁵ cells per ml were incubated in triplicates for 72 hoursin 0.2 ml of culture medium in microtiter wells in the presence 10 □g/mloxidized LDL. Proliferation was measured by the incorporation of[³H]-thymidine into DNA during the final 12 hours of incubation. Theresults are expressed as the stimulation index (S.I.): the ratio of themean radioactivity (cpm) of the antigen to the mean background (cpm)obtained in the absence of the antigen. Standard deviation was always<10% of the mean cpm.

RT-PCR analysis: Aortas were removed out of treated and untreated mice(in a sterile manner) and freezed in liquid nitrogen. The aorta weremashed on screen cup and the RNA production was performed using Rneasykit (QIAGEN). RNA samples were examined in spectrophotometer andnormalized relative to □-actin. Reverse transcription of RNA to cDNA andPCR with primers was performed with “Titan one tube RT-PCR kit” (ROCHE).Results were detected on 1% agarose gel and were documented on film.

Statistical Analysis: A one way ANOVA test was used to compareindependent values. p<0.05 was accepted as statistically significant.

Example I Synthesis of the Tolerizing/Immunizing Antigens 2,5-AldehydeLecithin Ether (ALLE) and POVPC

Synthesis of 25′-Aldehyde Lechitin Ether (ALLE)

2,5′-Aldehyde Lecithin Ether (ALLE) was synthesized according to amodification of general methods for synthesis of ether analogs oflecithins communicated by Eibl H., et al. Ann. Chem. 709:226-230,(1967), W. J. Baumann and H. K. Mangold, J. Org. Chem. 31, 498 (1996),E. Baer and Buchnea JBC. 230, 447 (1958), Halperin G et al Methods inEnzymology 129, 838-846 (1986). The following protocol refers tocompounds and processes depicted in 2-D form in FIG. 1.

Hexadecyl-glycerol ether D-Acetone glycerol (4 grams) for synthesis ofL-ALLE or L-Acetone glycerol for synthesis of D-ALLE, powdered potassiumhydroxide (approximately 10 grams) and hexadecyl bromide (9.3 grams) inbenzene (100 ml) were stirred and refluxed for 5 hours, while removingthe water formed by azeotropic distillation (compare W. J. Baumann andH. K. Mangold, J. Org. Chem. 29: 3055, 1964 and F. Paltauf, Monatsh.99:1277, 1968). The volume of the solvent was gradually reduced to about20 ml, and the resulting mixture was cooled to room temperature anddissolved in ether (100 ml). The resulting solution was washed withwater (2×50 ml), and the solvent was removed under reduced pressure. A100 ml mixture of 90.10:5 methanol:water:concentrated hydrochloric acidwas added to the residue and the mixture was refluxed for 10 minutes.The product was extracted with ether (200 ml) and was washedconsecutively with water (50 ml), 10% sodium hydroxide (20 ml) and againwith water (volumes of 20 ml) until neutral. The solvent was removedunder reduced pressure and the product (8.8 grams) was crystallized fromhexane to give 7.4 grams of pure 1-hexadecyl-glyceryl ether (compound I,FIG. 1) for synthesis of D-ALLE or 3-hexadecyl-glyceryl ether forsynthesis of L-ALLE.

5-Hexenyl-methane sulfonate: A mixture of 5-hexene-1-ol (12 ml) and drypyridine (25 ml) was cooled to between −4° C. and −10° C. in an ice-saltbath. Methanesulfonyl chloride (10 ml) was added dropwise during aperiod of 60 minutes, and the mixture was kept at 4° C. for 48 hours.Ice (20 grams) was added, the mixture was allowed to stand for 30minutes, and the product was extracted with ether (200 ml). The organicphase was washed with water (20 ml), 10% hydrochloric acid, 10% sodiumbicarbonate (20 ml) and again with water (20 ml). The solvent wasevaporated and the crude product was chromatographed on silica gel 60(100 grams) using a mixture of 80:20 CHCl₃:EtOAc as eluent, to give 14grams of 5-hexenyl-methane sulfonate.

1-Hexadecyloxy-3-trityloxy-2-propanol (for D-ALLE) or3-Hexadecyloxy-1-trityloxy-2-propanol (for L-ALLE) (compound II):1-Hexadecyloxy-glycerol (for D-ALLE) or 3-Hexadecyloxy-glycerol (forL-ALLE) (7.9 grams), triphenylchloromethane (8.4 grams) and dry pyridine(40 ml) were heated at 100° C. for 12 hours. After cooling, 300 ml ofether and 150 ml of ice-cold water were added, and the reaction mixturewas transferred to a separatory funnel. The organic phase was washedconsecutively with 50 ml of ice water, 1% potassium carbonate solution(until basic) and 50 ml of water, then dried over anhydrous sodiumsulfate. The solvent was evaporated, the residue was dissolved in 150 mlof warm petroleum ether and the resulting solution was cooled at 4° C.over night. After filtration of the precipitate, the filtrate wasevaporated and the residue was recrystallized from 20 ml of ethylacetate at −30° C., yielding 8.2 grams of1-Hexadecyloxy-3-trityloxy-2-propanol (for D-ALLE) or3-hexadecyloxy-1-trityloxy-2-propanol (for L-ALLE) (compound II, FIG.1), melting point 49° C.

1-Hexadecyl-2-(5′-hexenyl)-glyceryl ether (for D-ALLE) or3-hexadecyl-2-(5′-hexenyl)-glyceryl ether (for L-ALLE) (compound IV):1-Hexadecyloxy-3-trityloxy-2-propanol (for D-ALLE) or3-Hexadecyloxy-1-trityloxy-2-propanol (for L-ALLE) (compound II, FIG. 1)(5.5 grams) was etherified with 5-hexenyl-methanesulfonate, usingpowdered potassium hydroxide in benzene solution as described above. Thecrude product 1-Hexadecyloxy-2-(5′-hexenyloxy-1-sn-3-trityloxy-propane(for D-ALLE) or 3-Hexadecyloxy-2-(5′-hexenyloxy)-sn-3-trityloxy-propane(for L-ALLE) (compound III, FIG. 1) was dissolved in 100 ml of 90:10:5methanol:water:concentrated hydrochloric acid and the mixture wasrefluxed for 6 hours. The product was extracted with ether, washed withwater and the solvent was removed. The residue was dissolved inpetroleum ether (100 ml) and was kept in 4° C. for overnight, causingmost of the triphenyl carbinol to be deposited. After filtration andremoval of the solvent from the filtrate the crude product waschromatographed on silica gel 60 (40 grams), using a mixture of 1:1chloroform:petroleum ether as eluent, to give 1.8 grams of pure1-hexadecyl-2-(5′-hexenyl)-glyceryl ether (for D-ALLE) or3-hexadecyl-2-(5′-hexenyl)-glyceryl ether (for L-ALLE) (compound IV,FIG. 1).

1-Hexadecyl-2-(5′-hexenyl)-sn-glycero-3-phosphocholine (for D-ALLE) or3-Hexadecyl-2-(5′-hexenyl)-sn-glycero-1-phosphocholine (for L-ALLE)(compound V): The following procedure is a modification of the methodcommunicated by Eibl H., et al. Ann. Chem. 709:226-230, 1967.

A solution of 1-hexadecyl-2-hexenyl-glyceryl ether (for D-ALLE) or3-hexadecyl-2-hexenyl-glyceryl ether (for L-ALLE) (compound IV, FIG. 1)(2 grams) in dry chloroform (15 ml) was added dropwise into a stirred,cooled solution (−4° C. to −10° C.) of dry triethylamine (3 ml) and2-bromoethyl dichlorophosphate (1.25 ml, prepared as describedhereinbelow) in dry chloroform (15 ml), during a period of 1 hour. Themixture was kept at room temperature for 6 hours and then heated to 40°C. for 12 hours. The resulting dark brown solution was cooled to 0° C.and 0.1M potassium chloride (15 ml) was added. The mixture was allowedto reach room temperature and was stirred for 60 minutes. Methanol (25ml) and chloroform (50 ml) were added and the organic phase was washedwith 0.1M hydrochloric acid (20 ml) and water (20 ml). The solvent wasevaporated and the crude product was dissolved in methanol (15 ml), thesolution was transferred to a culture tube and was cooled in an ice-saltbath. Cold trimethylamine (3 ml, −20° C.) was added and the tube wassealed. The mixture was heated to 55° C. for 12 hours, cooled to roomtemperature and the solvent evaporated using a stream of nitrogen. Theresidue was extracted with a mixture of 2:1 chloroform:methanol (25 ml)and washed with 1M potassium carbonate (10 ml) and water (2×10 ml). Thesolvent was removed under educed pressure and the crude products werechromatographed on silica gel 60 (20 grams), using a mixture of 60:40chloroform:methanol, to give 1.5 grams of1-hexadcyl-2-(5′-hexenyl)-sn-glycero-3-phosphocholine (for D-ALLE) or3-hexadcyl-2-(5′-hexenyl)-sn-glycero-1-phosphocholine (for L-ALLE)(compound V, FIG. 1). The structure of compound V was confirmed by NMRand mass spectrometry.

1-Hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphocholine (for D-ALLE)or 3-Hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-1-phosphocholine (forL-ALLE) (compound VI):

A solution of Compound V (0.5 gram) in formic acid (15 ml) and 30%hydrogen peroxide (3.5 ml) was stirred at room temperature over night.The reaction mixture was diluted with water (50 ml), and extracted witha mixture of 2:1 chloroform:methanol (5×50 ml). The solvent wasevaporated under reduced pressure and the residue was mixed withmethanol (10 ml) and water (4 ml), then stirred at room temperature for60 minutes. 80% phosphoric acid (2 ml) and potassium meta periodate (0.8gram) were then added. The mixture was kept at room temperatureovernight, diluted with water (50 ml) and extracted with 2:1chloroform:methanol (50 ml). The organic phase was washed with 10%sodium bisulfite (10 ml) and water (10 ml). The solvent was removedunder reduced pressure and the crude product was chromatographed onsilica gel 60 (10 grams), using a mixture of 1:1 chloroform:methanol aselunet, to give 249 mg of1-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphocholine (for D-ALLE)or 3-hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-1-phosphocholine (forL-ALLE) (compound VI, FIG. 1), exhibiting an R_(f) of 0.15 (TLC system,60:40:8 chloroform:methanol:water) and a positive reaction withdinitrophenylhydrazine. The chemical structure of Compound VI wasconfirmed by NMR and mass spectrometry.

In an alternative process, the ethylenic group was converted to analdehyde group by ozonization and catalytic hydrogenation with palladiumcalcium carbonate.

Preparation of 2-bromoethyl dichlorophosphate: 2-Bromoethyldichlorophosphate was prepared by dropwise addition of freshly distilled2-bromoethanol (0.5M, prepared as described in Gilman Org. Synth.12:117, 1926) to an ice-cooled solution of freshly distilled phosphorousoxychloride (0.5M) in dry chloroform, during a one hour period, followedby 5 hours reflux and vacuum distillation (bp 66-68° C. at 0.4-0.5 mmHg). The reagent was stored (−20° C.) under nitrogen in small sealedampoules prior to use (Hansen W. H et al., Lipids 17(6):453-459, 1982).

Synthesis of 1-Hexadecyl-2-(5′-carboxy-butyl)-sn-glycero-3-phosphcholine(CI-201)

1-Hexadecyl-2-(5′-oxo-pentanyl)-sn-glycero-3-phosphcholine (Compound VI,prepared as described above), 0.55 grams (0.001 mol), was dissolved int-BuOH (30 ml). A solution of NaClO₂ (0.9 gram, 0.01 mol) and NaH₂PO₄(0.96 gram, 0.07 mol) in 25 ml water was added dropwise during aperiodof 30 minutes and the mixture was stirred at room temperature for 3hours. The reaction mixture was acidified to pH=3 with concentratedhydrichloric acid and extracted with a mixture of 2:1chlroform:methanol. The organic phase was separated and the solvent wasevaporated. The residue was purified by chromatography over silica gelusing a mixture of chloroform:methanol:water (70:27:3), to give1-hexadecyl-2-(5′-carboxy-butyl)-sn-glycero-3-phosphcholine (0.42 gram,72% yield). NMR and mass spectrometry confirmed the chemical structure(Compound I, FIG. 10).

Synthesis of1-Hexadecyl-2-(5′,5′-dimethoxy-pentyloxy)-sn-glycero-3-phosphcholine

1-Hexadecyl-2-(5′-hexenyl)-sn-glycero-3-phosphcholine (compound V,prepared as described above), 0.50 gram (0.89 mmol), was dissolved informic acid (15 ml) and hydrogen peroxide 30% (3.5 ml) was added. Thereaction mixture was stirred overnight at room temperature. Afteraddition of water (50 ml) the product was extracted with a mixture of2:1 chloroform:methanol (2×50 ml). The organic phase was washed withaqueous 10% sodium bicarbonate (10 ml) and water (10 ml) and the solventwas removed under reduced pressure. The residue (0.4 gram) was dissolvedin methanol (10 ml), aqueous 10% sodium hydroxide (4 ml) was then addedand the reaction mixture was stirred at room temperature for 1 hour. 80%Phosphoric acid (2 ml) and potassium meta periodate (0.8 gram) werethereafter added and stirring was continued for over night. A mixture of2:1 chloroform:methanol (50 ml) was then added and the organic phase waswashed with aqueous 10% sodium bisulfite (10 ml) and water (10 ml), andthe solvent was removed under vacuum. The residue (0.3 gram) waspurified by chromatography over silica gel (10 grams) using a mixture ofchloroform:methanol (60:40 to 40:60) as graduated eluent, to give1-hexadecyl-2-(5′,5′-dimethoxy-pentyloxy)-sn-glycero-3-phosphcholine(0.25 gram, 46% yield). NMR and mass spectrometry confirmed the chemicalstructure (Compound IIa, FIG. 10).

Synthesis of1-Hexadecyl-2-(5′,5′-diethoxypentyloxy)-sn-glycero-3-phosphocholine

Crude 1-Hexadecyl-2-(5′-hexenyl)-sn-glycero-3-phosphcholine (compound V,prepared as described above), 50 mg (0.088 mmol), was dissolved inethanol (10 ml), under a nitrogen atmosphere. Triethyl orthoformate(0.053 ml, 0.0476 gram, 0.32 mmol) and 3 drops of conc. sulfuric acidwere added and the reaction mixture was stirred overnight at roomtemperature. Dichloromethane (75 ml) was then added and the reactionmixture was transferred to a separatory funnel washed successively withwater (75 ml), aqueous 2.5% sodium bicarbonate solution (75 ml) andwater (75 ml), and was dried over anhydrous sodium sulfate. Afterfiltration, the solvent was removed under vacuum, to give 50 mg of crude1-hexadecyl-2-(5′,5′-diethoxypentyloxy)-sn-glycero-3-phosphocholine. Thestructure was confirmed by CMR and MS spectroscopy (Compound IIb, FIG.10).

Synthesis of1-Hexadecanoyl-2-(5′-oxo-pentanoyl)-sn-3-glycerophosphocholine(POVPC)

A mixture of 1-hexadecanoyl-sn-3-glycerophosphocholine (compound I, FIG.2), L-□-palmitoyl-lysophosphatidylcholine (3 grams), 5-hexenoic acid(1.2 ml), 1,3-dicyclohexylcarbodiamide (DCC, 4.05 grams) andN,N-dimethylaminopyridine (DMP, 1.6 grams) in dichloromethane (100 ml,freshly distilled from phosphorus pentoxide) was thoroughly stirred for4 days at room temperature. The mixture was then chromatographed onsilica gel 60 (40 grams) and the product,1-hexadecanoyl-2-(5′-hexenoyl)-sn-3-glycerophosphocholine (2.8 grams,compound II, FIG. 2) was eluted with a mixture of 25:75chloroform:methanol. The eluent was dissolved in 30% hydrogenperoxide:formic acid (4:15) and the solution was stirred overnight atroom temperature. Water (50 ml) were added, the product was extractedwith 2:1 chloroform:methanol (100 ml) and the organic phase was washedwith water. The solvent was evaporated under reduced pressure, theresidue was dissolved in methanol (15 ml) and 10% ammonia solution (5ml) and the solution was stirred at room temperature for 6 hours. Thecrude1-hexadecanoyl-2-(5′,6′-dihydroxy)-hexanoyl-sn-3-glycerophosphocholine(compound III, FIG. 2) (structure confirmed by NMR and massspectrometry) was further reacted without puirofocation. 80% phosphoricacid (3 ml) and sodium metaperiodate (1 gram) were added to the solutionand the mixture was stirred at room temperature for overnight, and wasthereafter extracted with a mixture of 2:1 chloroform:methanol. Theproduct was purified by chromatography on silica gel 60 (20 grams),using a mixture of 25:75 chloroform:methanol as eluent. 850 mg of1-hexadecanoyl-2-(5′-oxopentanoyl)-sn-3-glycerophosphocholine (POVPC,compound IV, FIG. 2) were obtained, exhibiting chromatographic mobilityof lecithin on TLC, and positive dinitrophenyl hydrazine reaction. Thestructure was assessed by NMR and mass spectrometry.

Alternatively: the ethylenic group was converted to an aldehyde byozonization and catalytic hydrogenation with palladium calciumcarbonate.

Example II Immunization Against L-ALLE+D-ALLE Specifically InhibitsAtherogenesis in Genetically Disposed (apoE-Knock Out) Mice

The present inventors have demonstrated that immunization with thestable, etherified synthetic LDL component ALLE can reduce the extent ofatherosclerotic plaque formation in susceptible mice. 19 female 5-7weeks old Apo E/C 57 mice were divided into 3 groups. In group A (n=6)the mice were immunized intreperitoneally, as described in Materials andMethods section above, with 150 μg/mouse L-ALLE+D-ALLE once every 2weeks (0.3 ml/mouse) X4. In group B (n=6) the mice were immunized withtuberculin toxin Purified Protein Derivative (PPD) once every 2 weeks(0.3 ml/mouse). In group C (n=7) the mice received no immunization. Micefrom all three groups were bled prior to immunization (Time 0), and atone week after the second immunization for determination of anti-ox LDLantibodies, anti-ALLE antibodies and lipid profile. Atherosclerosisassessment was performed as described above, 4.5 weeks post 4^(th)immunization. The mice from all groups were weighed at 2 week intervalsthroughout the experiment. All mice were fed normal chow-diet containing4.5% fat by weight (0.02% cholesterol) and water ad libitum.

TABLE I Immunization of apoE knock out mice with ALLE inhibitsatherogenesis 150 μg/Mouse L-ALLE ± Control D-ALLE without immunizationPPD immunization Groups N = 6 N = 5 N = 7 Statistics Time 0 Weight 17.3± 0.5 17.3 ± 0.7 17.8 ± 0.4 P = 0.780 Chol 435 ± 47 436 ± 49 413 ± 44 P= 0.919 TG 118 ± 9  112 ± 10 120 ± 14 P = 0.865 End Weight 20.5 ± 0.521.6 ± 0.2 20.3 ± 0.5 P = 0.123 Chol 299 ± 18 294 ± 15 3044 ± 22  P =0.937 TG 57 ± 3 53 ± 4 66 ± 4 P = 0.075 Lesion 101000 ± 8276  179500 ±13449 210833 ± 26714 P = 0.005 size (μm²) TGF-□ 12032 ± 2308 13963 ±944  12825 ± 2340 P = 0.831 pmol/ml

As can be seen in FIG. 3, the results depicted in Table I demonstratethe significant reduction in atheromatous lesions measured in the hearttissues of the ALLE immunized mice, compared to both PPD and unimmunizedcontrol mice. No significant effect is apparent on other parametersmeasured, such as weight gain, triglyceride or cholesterol blood levels,or immune competence, as measured by the levels of the immunosuppressivecytokine TGF-β. Thus, immunization with the synthetic oxidized LDLcomponent ALLE (a mixture of racemic forms D- and L-) conferssignificant (>50%) protection from atherosclerotic lesion formation inthese genetically susceptible apoE-knockout mice. A significant but lessdramatic reduction in plaquing was observed in mice immunized with PPD.

Example III Inhibition of Atherogenesis in Genetically Predisposed(apoE-Knockout) Mice by induction of oral tolerance with L-ALLE andD-ALLE

Intraperitoneal immunization with the ester analogs of plaque lesioncomponents was effective in inhibiting atherogenesis in apoE-knockoutmice (FIG. 1). Thus, the ability of L- and D-ALLE to suppressatherogenesis through oral tolerance was investigated. 34 male 8-10 weekold Apo E knock out mice were divided into three groups. In group A(n=11) oral tolerance was induced by administration by gavage ofL-ALLE+D-ALLE suspended in PBS (1 mg/mouse) for 5 days every other day.In group B (n=11) mice received 10 μg/mouse L-ALLE+D-ALLE suspended inPBS for 5 days every other day. (0.2 ml/mouse). Mice in group C (n=12)received PBS (containing the same volume of ethanol as in groups A+B).Mice were bled prior to feeding (Time 0) and at the conclusion of theexperiment (End) for determination of lipid profile. Atherosclerosis wasassessed in heart, aorta, and serum as described above 8 weeks after thelast feeding. Mice were weighed every 2 weeks during the experiment. Allmice were fed normal chow-diet containing 4.5% fat by weight (0.02%cholesterol) and water ad libitum.

TABLE 2 Inhibition of atherogenesis in apoE-knock out mice by oraladministration of L-ALLE and D-ALLE PBS 1 mg ALLE 10 μg ALLE Groups N =12 N = 11 N = 11 Statistics Time 0 Weight 20.7 ± 0.6 21.5 ± 0.8 21.1 ±0.8 P = 0.794 Chol 373 ± 25 379 ± 23 378 ± 31 P = 0.983 TG 128 98 90 P =0.829 End Weight 27.3 ± 0.4 27.4 ± 0.5 24.1 ± 0.8 P < 0.001 Chol 303 ±17 249 ± 24 321 ± 15 P = 0.031 TG 81 ± 4 78 ± 8 93 ± 6 P = 0.146 Lesion176000 ± 13735  85278 ± 11633 103889 ± 14320 P < 0.001 size (μm²) TGF-β14696 ± 1352 13388 ± 1489 18010 ± 1373 P = 0.07 pmol/ml Note: “Weight”is weight in grams; “Chol” is serum cholesterol and “TG” is serumtriglycerides, expressed in mg/dL.

As can be seen from FIG. 4, the results depicted in Table 2 demonstratea striking attenuation of atherosclerotic progression measured in thetissues of mice fed low doses (10 μg-1 mg/mouse) of ALLE, compared tounexposed control mice. No significant effect is apparent on otherparameters measured, such as weight gain, triglyceride or cholesterolblood levels, or immune competence, as measured by the levels of theimmunosuppressive cytokine TGF-β. Thus, the synthetic oxidized LDLcomponent ALLE is a potent inducer of oral tolerance, conferringsignificant (>50%) protection from atherosclerosis in these geneticallysusceptible apoE-knock out mice, similar to the protection achieved withperitoneal immunization (see FIG. 1).

Example IV Inhibition of Atherogenesis in Genetically Predisposed(apoE-Knock Out) Mice by Induction of Oral and Nasal Tolerance withL-ALLE

Mechanisms of mucosal tolerance are active in the nasal mucosa as wellas the gut. Thus, nasal exposure and oral exposure to L- and D-ALLE werecompared for their effectiveness in suppressing atherogenesis inapoE-knockout mice. 34 male 7-10 weeks old Apo E knock out mice weredivided into 3 groups. In group A (n=11) oral tolerance was induced byadministration by gavage of L-ALLE suspended in PBS (1 mg/mouse/0.2 ml)for 5 days every other day. In group B (n=11) nasal tolerance wasinduced as described in Materials and Methods by administration of 10μg/mouse/10 □L-ALLE suspended in PBS every other day for 3 days. Mice ingroup C (n=12) received PBS administered orally and nasally (containingthe same volume of ethanol as in groups A+B). Mice were bled prior tofeeding (Time 0) and at the conclusion of the experiment (End) fordetermination of lipid profile. Atherosclerosis was assessed in heartand aorta as described above, 8 weeks after the last feeding. Mice wereweighed every 2 weeks during the experiment. All mice were fed normalchow-diet containing 4.5% fat by weight (0.02% cholesterol) and water adlibitum.

TABLE 3 Inhibition of atherogenesis in apoE- knock out mice by nasaladministration of L-ALLE 1 mg 10 μg ALLE ALLE PBS Oral Nasal Oral Groups(N = 11) (N = 11) (N = 12) Statistics Time 0 Weight 21.1 ± 0.8 21.1 ±0.7 22.1 ± 0.9 P = 0.624 Chol 362 ± 27 353 ± 31 351 ± 27 P = 0.952 TG144 143 138 P = 0.977 End Weight 23.3 ± 1.1 24.2 ± 0.2 24.0 ± 0.5 P =0.558 Chol 418 ± 43 328 ± 18 343 ± 25 P = 0.084 TG 82 ± 7 74 ± 6 79 ± 5P = 0.630 Lesion  76944 ± 17072  82708 ± 10986 135455 ± 12472 P = 0.007size (μm²) Note: “Weight” is weight in grams; “Chol” is serumcholesterol and “TG” is serum triglycerides, expressed in mg/dL.

As can be seen from FIG. 5, the results depicted in Table 3 demonstrateeffective (as effective as oral tolerance) inhibition of atherogenesismeasured in the tissues of mice receiving nasal exposure to low doses(10 μg/mouse) of ALLE, compared to unexposed control mice. Induction ofnasal tolerance, like oral tolerance, had no significant effect on otherparameters measured, such as weight gain, triglyceride or cholesterolblood levels. Thus, the synthetic oxidized LDL component ALLE is apotent inducer of nasal as well as oral tolerance, conferringsignificant (approximately 50%) protection from atherogenesis in thesegenetically susceptible apoE-knock out mice, similar to the protectionachieved induction of oral tolerance alone.

Example V Suppression of Specific Anti-ox LDL Immune Reactivity inGenetically Predisposed (apoE-Knock Out) Mice by Oral Administration ofL-ALLE or POVPC

Tolerance induced by mucosal exposure to oxidized analogs of LDL may bemediated by suppression of specific immune responses to theplaque-related antigens. POVPC(1-Hexadecanoyl-2-(5′-oxo-pentanoyl)-sn-glycerophosphocholine) is anon-ether oxidized LDL analog, which, unlike ALLE is susceptible tobreakdown in the liver. Lymphocyte proliferation in response to oralexposure to both POVPC and the more stable analog ALLE was measured inapoE-knock out mice. 8 male, 6 week old Apo Eknock out mice were dividedinto 3 groups. In group A (n=2) oral tolerance was induced with 1mg/mouse L-ALLE suspended in 0.2 ml PBS, administered by gavage, asdescribed above, every other day for 5 days. In group B (n=3) oraltolerance was induced with 1 mg/mouse POVPC suspended in 0.2 ml PBS,administered per os as described above, every other day for 5 days. Themice in group C (n=3) received oral administration of 200 μl PBS everyother day for 5 days. Immune reactivity was stimulated by immunizationwith Human oxidized LDL as described above in the Materials and Methodssection, one day after the last feeding. One week after the immunizationlymph nodes were collected for assay of proliferation. All mice were fednormal chow-diet containing 4.5% fat by weight (0.02% cholesterol) andwater ad libitum.

TABLE 4 Oral pretreatment with synthetic oxidized LDL (ALLE and POVPC)suppresses immune response to Human ox- LDL in apoE-knock out miceStimulation index (SI) PBS POVPC L-ALLE statistics 33.1 ± 6.1 10.6 ± 2.37.3 ± 2.3 P < 0.01 N = 3 N = 3 N = 2 −68% −78%

As can be seen from FIG. 6, the results depicted in Table 4 demonstratesignificant suppression of immune reactivity to Human oxidized-LDLantigen, measured by inhibition of proliferation in the lymph nodes ofapoE-knock out mice. Lymphocytes from mice receiving oral exposure toatherogenesis-inhibiting doses (1 mg/mouse) of ALLE or POVPC showed areduced stimulation index following immunization with ox-LDL, ascompared to control (PBS) mice. Since induction of oral, like nasal,tolerance had no significant effect on other parameters measured, suchas weight gain, triglyceride or cholesterol blood levels, or immunecompetence (see Tables 1, 2 and 3), these results indicate a specificsuppression of anti-ox-LDL immune reactivity. Thus, oral administrationof the synthetic oxidized LDL component L-ALLE is an effective method ofattenuating the cellular immune response to immunogenic and atherogenicplaque components in these genetically susceptible apoE-knock out mice.FIG. 4 also demonstrates a similar, if less effective inhibition ofproliferation with oral administration of the less stable syntheticoxidized LDL component POVPC.

Example VI Inhibition of Atherogenesis in Genetically Predisposed(apoE-Knock Out) Mice by Induction of Oral Tolerance with D- andL-Isomers of ALLE, and POVPC

Since feeding of ALLE and POVPC was shown to inhibit early atherogenesisand immune reactivity to plaque-related Human LDL antigen, the abilityof both D- and L-isomers of the ether LDL analog, and the non-etheranalog POVPC to suppress the progression of atherogenesis in older micewas compared. Their effect on the triglyceride and cholesterol fractionsof VLDL was also monitored by FPLC. 57 male, 24.5 week old Apo Eknockout mice were divided into 5 groups. In group A (n=11) oral tolerancewas induced with 1 mg/mouse L-ALLE suspended in 0.2 ml PBS, administeredby gavage, as described above, every other day for 5 days. In group B(n=9) oral tolerance was induced with 1 mg/mouse D-ALLE suspended in 0.2ml PBS, administered per os, as described above, every other day for 5days. In group C (n=10) oral tolerance was induced with 1 mg/mouse POVPCsuspended in 0.2 ml PBS, administered by gavage, as described above,every other day for 5 days. Control group D (n=10) received oraladministration of PBS (containing the same volume of ethanol as ingroups A, B, C). Base line group was sacrificed on time=0. Oraladministration of the tested antigens took place every 4 weeks (5 oralfeedings; every other day) starting at 24.5 weeks age, during 12 weeks(3 sets of feedings).

Mice were bled prior to feeding (Time 0), after the 2^(nd) set offeeding and at the conclusion of the experiment (End) for determinationof lipid profile, lipid fractionation and plasma collection.Atherosclerosis was assessed as described above in the heart and aortaand spleens collected for proliferation assay 12 weeks after the firstfeeding. Weight was recorded every 2 weeks throughout the experiment.All mice were fed normal chow-diet containing 4.5% fat by weight (0.02%cholesterol) and water ad libitum.

TABLE 5 Inhibition of atherogenesis in apoE-knock out mice by oraladministration of L-ALLE, D-ALLE and POVPC 1 mg 1 mg 1 mg Base line TimeParameter PBS L-ALLE D-ALLE POVPC (t = 0) point tested (n = 10) (n = 11)(n = 9) (n = 10) (n = 8) statistics 0 Weight 28.1 ± 0.5   29 ± 0.6 29.8± 0.7 29.6 ± 0.7 29.8 ± 1.1 P = 0.445 Cholesterol 413 ± 27 413 ± 23 409± 28 401 ± 21 393 ± 16 P = 0.976 Triglyceride 67 ± 5 63 ± 8 63 ± 4 67 ±7 71 ± 8 P = 0.946 End Weight 28.5 ± 0.6 29.7 ± 0.5 30.4 ± 0.8 29.9 ±0.5 — P = 0.177 Cholesterol 365 ± 15 391 ± 18 394 ± 15 358 ± 28 — P =0.481 Triglyceride 84 ± 4 83 ± 4 94 ± 4 85 ± 3 — P = 0.207 Sinus Lesion369688 ± 32570 233056 ± 12746 245938 ± 20474 245750 ± 20423 225,714 ±5,869  P < 0.001 □m² Aorta lesion 4.5 5.4 4.5 8.3 1.4 P = 0.002 (% fromtotal area) Note: “Weight” is weight in grams; “Cholesterol” is serumcholesterol and “Triglyceride” is serum triglycerides, expressed inmg/dL.

As can be seen from FIG. 7, the results depicted in Table 5 demonstrateeffective inhibition of late stage atherogenesis measured in the tissuesof older mice following protracted oral exposure to moderately low doses(1 mg/mouse) of the D- and L-isomers of ALLE, and POVPC compared toPBS-fed control mice. Induction of oral tolerance had no significanteffect on other parameters measured, such as weight gain, totaltriglyceride or cholesterol blood levels. Thus, the synthetic oxidizedLDL components D-, L-ALLE and POVPC are individually potent inducers oforal tolerance, conferring nearly complete protection from atheromatousprogression (as compared with lesion scores at 24.5 weeks) in thesegenetically susceptible apoE-deficient mice. Surprisingly, it wasobserved that the inhibition of atherogenesis by these oxidized LDLanalogs is accompanied by a significant reduction in VLDL cholesteroland triglycerides, as measured by FPLC (FIGS. 8 and 9).

Example VII Inhibition of Atherogenesis in Genetically Predisposed(apoE-Knock Out) Mice by Induction of Oral Tolerance with CI-201

The ability of a stable form of an etherified phospholipid, the acidderivative of ALLE IC-201, to suppress atherogenesis through oraltolerance was investigated. Male 12 week old ApoE KO mice were dividedinto two groups. In group A (n=14) oral tolerance was induced byadministration by gavage of CI-201 (0.025 mg/dose) suspended in PBS for8 weeks every day (5 times a week). Mice in group B (n=15) received PBS(control). Atherosclerosis was assessed as described above. All micewere fed normal chow-diet containing 4.5% fat by weight (0.02%cholesterol) and water ad libitum.

As can be seen from FIG. 11, the results demonstrate a strikingattenuation of atherosclerotic progression measured in the tissues ofmice fed low doses of CI-201, as compared with unexposed control mice(PBS). Aortic sinus lesion in the CI-201 treated group was125,192±19,824 μm² and in the control group (PBS treated) was185,400±20,947 μm², demonstrating a decrease of 33% (P=0.051) of theaortic sinus lesion by oral administration of CI-201 in low dose. IL-10expression in the aorta was higher by 40% in the CI-201 treated group,as compared with the control group. The elevated expression levels ofIL-10 in the target organ, the aorta, support the induction of oraltolerance by CI-201 administration. Thus, the stable synthetic oxidizedLDL −201, was also found to be a potent inducer of oral tolerance.

Example VIII Cytokine Expression in the Aorta of Mice Treated withOxidized Phospholipids (ALLE, CI-201, Et-acetal, Me-acetal & oxLDL) inApoE Knock Out Mice

The effect of ALLE, CI-201, its corresponding acetal derivativesEt-acetal and Me-acetal (Compounds IIa and IIb, FIG. 10) and oxLDL oncytokine expression in the target organ—the aorta—was evaluated usingRT-PCR as described hereinabove. ApoE knock out mice were orallyadministered with 1 mg/mouse ALLE, 1 mg/mouse CI-201, 1 mg/mouseEt-acetal, 1 mg/mouse Me-acetal, 0.1 mg/mouse oxLDL or 0.2 ml/mouse PBS.Oral administrations took place 5 times every other day. The expressionof the anti-inflammatory cytokine IL-10 and the proinflammatory cytokineIFN-□ and IL-12 were determined 8 weeks after final oral administration.

As can be seen in FIGS. 12 a and 12 b, mice treated with ALLE, CI-201,Et-acetal, Me-acetal and oxLDL showed elevated levels of IL-10 ascompared with the control PBS-treated group. As can be seen in FIGS. 12c and 12 d, an opposite effect was shown in the expression level ofIFN-gamma and IL-12. Reduced expression levels of IFN-gamma wasdetectable in mice treated with ALLE, CI-201, Me-acetal and oxLDL andreduced levels of IL-12 was detectable in mice treated with ALLE,CI-201, Et-acetal and oxLDL.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

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1. A method of synthesizing an oxidized phospholipid comprising: (a) providing a phospholipid backbone including two fatty acid side chains, wherein at least one of said fatty acid side chains is a mono-unsaturated fatty acid having 2-15 carbon atoms; and (b) oxidizing the unsaturated bond of said mono-unsaturated fatty acid to thereby generate the oxidized phospholipid.
 2. The method of claim 1, wherein said phospholipid backbone further includes a moiety selected from the group consisting of H. phosphoryl choline, phosphoryl ethanolamine, phosphoryl serine, phosphoryl cardiolipin and phosphoryl inisitol.
 3. The method of claim 1, wherein the oxidized phospholipid is POVPC, and said mono-unsaturated fatty acid is 5-hexenoic acid. 